Absorbent articles with nits and free-flowing particles

ABSTRACT

Absorbent articles comprising fibrous nits and other free-flowing particles are disclosed. In one embodiment, an absorbent article is disclosed comprising free-flowing particles in a central portion which, in conjunction with other absorbent members, provides excellent body fit and good fluid handling performance. In another embodiment, good leakage control is provided by the combined effect of good intake and fluid handling performance of fibrous nits coupled with a wicking barrier between the nits and the longitudinal sides of the articles. An optional central rising member can further enhance the topography of the article when compressed by urging the portion comprising nits to deflect vertically upward. 
     Methods of preparing cellulosic nits and incorporating them into absorbent articles are also described.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.09/547,203; filed 12 Apr. 2000, now U.S. Pat. No. 6,667,424 which inturn is a continuation in part of the following applications: Ser. No.09/165,875, “Absorbent Article with Center Fill Performance,” filed Oct.2, 1998 now U.S. Pat. No. 6,673,982; Ser. No. 09/165,871, “AbsorbentArticle Having Good Body Fit Under Dynamic Conditions,” also filed Oct.2, 1998, now U.S. Pat. No. 6,503,233, issued Jan. 7, 2003; provisionalapplication Ser. No. 60/129,752, “Method of Making an Absorbent ArticleContaining Eucalyptus Nits,” filed Apr. 16, 1999; and provisionalapplication Ser. No. 60/129,746, “Absorbent Article with Nits andFree-Flowing Particles,” also filed Apr. 16, 1999.

BACKGROUND OF THE INVENTION

Absorbent articles for collecting body exudates typically comprise bulkyfibrous absorbent webs as the main absorbent material for collectingbody fluids. These webs often collapse when wetted, resulting indecreased void volume and degraded body-fit after the article is wetted.They also often lack the ability to conform well to the body of awearer. What is needed are improved absorbent articles or absorbentmaterials capable of overcoming various limitations of past approaches.More specifically, improved materials and articles are needed that arecapable of providing at least one of improved body fit, conformability,maintenance of void volume when wet or absorbency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart depicting one choice of process steps forpreparing free-flowing particles for use in absorbent articles.

FIG. 2 depicts a sanitary napkin of the present invention incross-sectional view showing an intake member comprising a longitudinalpouch of nits.

FIG. 3 is a cross-sectional view of an absorbent article of the presentinvention with a conformable intake member comprising free-flowingparticles and further comprising a wicking barrier to impede fluid flowfrom a central absorbent member to an outer absorbent member.

FIGS. 4A and 4B depict cross-sectional views of two versions of anabsorbent article having a pouch of nits or free-flowing particlesbeneath an upper absorbent layer, wherein the pouch helps predispose theupper absorbent layer for upward flexing when the article is worn.

FIG. 5 is a partial cutaway view of a sanitary napkin comprising a pouchof nits or free-flowing particles disposed between two absorbent layers.

FIGS. 6A-6C depict embodiments in which a central pouch of nits orfree-flowing particles disposed on an absorbent layer can serve as aconformable intake member.

FIG. 7 depicts a cutaway view of an absorbent core comprising a wickingbarrier and a central absorbent member having an internal pouch offree-flowing particles.

FIG. 8 depicts a partial sectional view of a pad comprising a centralpillow filled with nits and/or other free-flowing particles.

FIG. 9 shows a simple apparatus for measuring the angle of repose offree-flowing particles.

FIG. 10 shows how the angle of repose is determined in a pile offree-flowing particles.

FIG. 11 depicts apparatus used to measure permeability of free-flowingparticles.

FIG. 12 depicts a bottom view of the apparatus of FIG. 11.

FIG. 13 is a flowchart for a method of preparing absorbent articlescomprising nits that have been disperged twice.

FIG. 14 is a flowchart for a method of preparing absorbent articles withtwo or more kinds of nits.

FIG. 15 is an SEM micrograph of a eucalyptus nit made according to thepresent invention.

FIG. 16 is an SEM micrograph of a eucalyptus nit with fibers projectingfrom the surface of the nit.

FIG. 17 is an SEM micrograph of the cross-section of a eucalyptus nitprepared with a Maule disperger.

DEFINITIONS AND TEST METHODS

As used herein, the term “absorbent article” refers to devices whichabsorb and contain liquids such as body exudates, and, morespecifically, refers to devices which are placed against or in proximityto the body of the wearer to absorb and contain the various exudatesdischarged from the body.

As used herein, “biodegradable” refers to the ability of a compound toultimately be degraded completely into carbon dioxide and water orbiomass by microorganisms and/or natural environmental factors. In oneembodiment, the free-flowing particles are substantially biodegradable.In another embodiment, the entire absorbent article is substantiallybiodegradable.

As used herein, “bulk” and “density,” unless otherwise specified, arebased on an oven-dry mass of a sample and a thickness measurement madeat a load of 0.34 kPa (0.05 psi) with a 7.62-cm (three-inch) diametercircular platen. Thickness measurements of samples are made in aTAPPI-conditioned room (50% relative humidity and 23° C.) afterconditioning for at least four hours. Samples should be essentially flatand uniform under the area of the contacting platen. Bulk is expressedas volume per mass of fiber in cc/g and density is the inverse, g/cc.

As used herein, the term “cellulosic” is meant to include any materialhaving cellulose as a major constituent, and specifically comprising atleast 50 percent by weight cellulose or a cellulose derivative. Thus,the term includes cotton, typical wood pulps, nonwoody cellulosicfibers, cellulose acetate, cellulose triacetate, rayon, thermomechanicalwood pulp, chemical wood pulp, debonded chemical wood pulp, milkweed,bacterial cellulose, and the like.

As used herein, “debonders” are chemicals which can be used to interferewith the normal hydrogen bonding that occurs between cellulosic fibersas they dry. Debonders generally comprise molecules with fatty portionsor alkyl chains or other moieties that hinder hydrogen bonding. In manycases, debonders are cationic, often comprising a quaternary aminegroup. However, it is within the scope of the invention to use adebonding agent which may be either cationic, nonionic or anionic innature. Without wishing to be limited by theory, it is believed that inaddition to interfering with hydrogen bonding, debonders can alsointerfere with ionic and covalent bonding between fibers and otherchemicals present in the web.

As used herein, the term “diaper” refers to an absorbent articlegenerally worn by infants and incontinent persons that is worn about thelower torso of the wearer.

The term “disposable” is used herein to describe absorbent articleswhich are not intended to be laundered or otherwise restored or reusedas an absorbent article (i.e., they are intended to be discarded after asingle use and optionally to be recycled, composted or otherwisedisposed of in an environmentally compatible manner).

As used herein, the term “dispersing” refers to mechanical processing ofmoist fibers at elevated consistency (e.g., greater than 8% andtypically greater than 10% consistency, such as from about 12% to about25% or from about 18% to about 42%) to cause the fibers to rub againsteach other without excessive damage to the fibers. Devices commonlyknown as kneaders or dispergers can be used, though both terms areencompassed by the term “disperger” as used herein. In this process, thefibers frequently become kinked or curled. Disperging is sometimescalled “dispersion” in the papermaking arts, where it has been appliedto modify fiber properties and enhance ink removal in recyclingoperations. Below, methods are presented for adapting dispergingoperations for the deliberate generation of fibrous nits—typically heldto be undesirable prior to the present invention.

As used herein, a “dispersant” is a chemical compound that helpsmaintain fine solid particles in a state of suspension and inhibitstheir agglomeration or settling in a fluid medium. The term “dispersant”is not to be confused with the aforementioned terms “disperging” and“dispersion” which, as used herein, refer to mechanical processing offibers. A variety of exemplary dispersants are disclosed in U.S. Pat.No. 5,795,377, issued Aug. 18, 1998 to Tanner et al., hereinincorporated by reference. With the help of mechanical agitation,dispersants can also promote the breaking up of agglomerates ofparticles to form particle suspensions. Overall, dispersants known inthe art are useful in preventing settling, deposition, precipitation,agglomeration, flocculation, coagulation, adherence or caking of solidparticles in a fluid medium. Suitable dispersants include: organicpolyelectrolytes including polycarboxylates, polysulfonates,polysulfates and polyphosphates; inorganic sulfonates, polyphosphatesand silicates; and polymers containing polar groups such aspolyacrylamides and polyols. Exemplary of synthetic polymer dispersantsare the co-polymers of ethylenically unsaturated monomers withmono-ethylenically unsaturated carboxylic acids or their partiallyneutralized salts. Examples of useful monounsaturated carboxylic acidsinclude acrylic acid, methacrylic acid, maleic acid, maleic anhydride,itaconic acid, itaconic anhydride, fumaric acid, half esters or halfamides of maleic, fumaric and itaconic acid, crotonic acids, alkylacrylates and methacrylates containing 1-18 carbon alkyl groups, vinylesters, vinylaromatic compounds, dienes, etc. Homopolymers ofmono-ethylenically unsaturated carboxylic acids or mixtures of thesemonomers may also be used. Examples include acrylic acid and methacrylicacid homopolymers and acrylic acid/methacrylic acid copolymers. Examplesof polyacrylamides of use include polyacrylamides andpolymethracrylamides and their N and N,N dialkyl derivatives containing1-18 carbon alkyl groups.

Exemplary of the sulfonic acid containing polymer dispersants are thehomopolymers of monoethylenically unsaturated sulfonic acids (or saltsthereof) and copolymers thereof with the aforementioned ethylenicallyunsaturated monomers. Suitable sulfonated containing monomers includearomatic sulfonic acids (such as styrene sulfonic acids, 2-vinylethylbenzenesulfonic acid, 2-vinyl-3-bromobenzenesulfonic acid,2-allylbenzene-sulfonic acid, vinylphenyl methanesulfonic acid),heterocyclic sulfonic acids (such as 2-sulfo-4-vinyl-furane and2-sulfo-5-allylfurane), and aliphatic sulfonic acids (such asethylenesulfonic acid and 1-phenylethylene sulfonic ac-id). Othersulfonated polymers of value in bringing about changes in the rheologyof particulate mixtures or slurries include calcium lignosulfonates,formaldehyde modified napthalene sulfonates, sulfonatedmelamine-formaldehyde polymers and other sulfonated polymers.

As used herein, “equivalent nit particle size” is meant to be a measureof the equivalent diameter of a nit as if the nit were assumed to bespherically shaped. The equivalent nit particle size may be quantified,for example, by sieving a nit sample. Alternatively, the equivalent nitparticle size for individual nits may be determined by an image analysismethod wherein a nit sample is placed on a glass plate and ahigh-resoltion picture is taken. From the measured area of a nit, theequivalent nit particle size can be calculated by assuming that the nitis circular across its cross-section. Nits useful in the presentinvention have an equivalent particle size that is greater than about150 micrometers and less than about 10 millimeters (mm), morespecifically greater than about 250 micrometers and less than about 5mm, and suitably greater than about 300 micrometers and less than about2 mm.

As used herein, the term “extensible” refers to articles that canincrease in at least one of their dimensions in the x-y plane by atleast 10% and specifically at least 20%. The x-y plane is a planegenerally parallel to the faces of the article. The term extensibleincludes articles that are stretchable and elastically stretchable(defined below). In the case of a sanitary napkin comprising anabsorbent core, for example, the article and the absorbent core can beextensible both in length and width. The absorbent article, however, mayonly be extensible in one of these directions such as the longitudinaldirection. The absorbent article comprising an absorbent core can, inaddition to being extensible, also be “stretchable”. The term“stretchable”, as used herein, refers to articles that are extensiblewhen stretching forces are applied to the article and offer someresistance to stretching. The terms “elastically stretchable” or“elastically extensible” are intended to be synonymous. These terms, asused herein, mean that when in-plane stretching forces are removed, thearticle or absorbent fibrous structure will tend to return toward itsunextended (original) dimensions. It need not return all the way to itsunextended dimensions, however. It may return to relaxed dimensionsbetween its unextended dimensions and maximum extended dimensions.

As used herein, the term “fiber” or “fibrous” is meant to refer to aparticulate material wherein the length to diameter ratio of suchparticulate material is greater than about 10 and specifically greaterthan about 20. Conversely, a “nonfiber” or “nonfibrous” material ismeant to refer to a particulate material wherein the length to diameterratio of such particulate material is about 10 or less.

As used herein, a bulk material (e.g., the absorbent components of thearticle) is considered “flexible” if a straight, TAPPI-conditioned (50percent relative humidity at 23° C.) strip of the material 25 cm longwith a cross-section of 1 cm×1 cm can be bent 180° around a 5-cmdiameter rod (i.e., wrapped around 50% of the perimeter of the rod)without breaking and without requiring application of more than 6Newtons of force to the ends of the strip to cause the bending over a3-second span of time. The same material is “shape retaining,” as usedherein, if the strip is held in place on the rod for 5 seconds and thenremains bent to an angle of at least 30° after the strip is removed fromthe rod (i.e., the strip is deformed such that the straight portions atthe ends of the strip are at an angle relative to each other of at least30°, with a perfectly straight strip defining an angle of 0°).

As used herein, the term “free flowing” refers to the ability ofparticulates to readily flow in response to shear forces typicallyencountered in the use of a sanitary napkin worn against a humanbody—forces similar to those obtained by gently rubbing fingers togetherwhile the fingers are immersed in the particles of interest. Dry, loose,granular materials such as hardwood nits and polymethylurea (PMU)particles (hereafter described) are generally free-flowing under suchconditions in contrast to materials such as clay which can deform butgenerally does not flow freely. Particularly, free-flowing particleswill have an angle of repose (hereafter described) less than about 70°in the dry state and specifically less than about 60°. Similarly, freeflowing particles will generally have high ratios of consolidationpressure (σ₁) to cohesive strength (f_(c)) measured according to theJenike shear flow test for particles, as specified in ASTM Test MethodD6128-97, “Standard Shear Testing Method for Bulk Solids Using theJenike Shear Cell,” herein incorporated by reference. This test examinesinterparticle shear forces under several loads and employs Mohr circleanalysis to obtain consolidation pressure and cohesive strength ofparticles, as well as the effective angle of internal friction (δ) andkinematic angle of internal friction (φ). Of most interest is the ratioof consolidation pressure to cohesive strength, which herein is termedthe “Flowability Coefficient.” Flowability Coefficients of about 1 orless are indicative of a poorly flowing or nonflowing material.Free-flowing particles will generally have a Flowability Coefficientgreater than about 2, specifically greater than about 2.5, morespecifically greater than about 3, and most specifically from about 3.5to about 10. Dry granular sand, a material with a very high flowabilityand low cohesive strength, can have a Flowability Coefficient of about10. Jenike shear testing is performed commercially by Jenike & Johanson,Inc. (Westford, Mass.). In one embodiment, the particles of the presentinvention also have an effective angle of internal friction (δ) of about67° or less, specifically about 60° or less, and most specifically about57° or less. Useful principles dealing with the rheological propertiesof granular particles are described by K. Shinohara in “Fundamental andRheological Properties of Powders,” Chapter 4 in Handbook of PowderScience and Technology, ed. by M. E. Fayed and L. Otten, 2^(nd) ed,Chapman & Hall, New York, 1887, pp. 96-145.

As used herein, “high yield pulp fibers” are those papermaking fibers ofpulps produced by pulping processes providing a yield of about 65percent or greater, more specifically about 75 percent or greater, andstill more specifically from about 75 to about 95 percent. Yield is theresulting amount of processed fiber expressed as a percentage of theinitial wood mass. High yield pulps include bleachedchemithermomechanical pulp (BCTMP), chemithermomechanical pulp (CTMP),pressure/pressure thermomechanical pulp (PTMP), thermomechanical pulp(TMP), thermomechanical chemical pulp (TMCP), high yield sulfite pulps,and high yield Kraft pulps, all of which contain fibers having highlevels of lignin. Characteristic high-yield fibers can have lignincontent by mass of about 1% or greater, more specifically about 3% orgreater, and still more specifically from about 2% to about 25%.Likewise, high yield fibers can have a kappa number greater than 20, forexample. The high yield pulp fibers, after being prepared by pulping andoptional bleaching steps and prior to being formed into dry bales orwebs, in one embodiment can also be characterized by being comprised ofcomparatively whole, relatively undamaged fibers, high freeness (200Canadian Standard Freeness (CSF) or greater, more specifically 250 CSFor greater, and still more specifically 400 CSF or greater), and lowfines content (less than 25 percent, more specifically less than 20percent, still more specifically less that 15 percent, and still morespecifically less than 10 percent by the Britt jar test known to thoseskilled in the art of papermaking). In one embodiment, the high-yieldfibers are predominately softwood and can be northern softwood BCTMP.

As used herein, the term “hydrophobic” refers to a material having acontact angle of water in air of at least 90 degrees. In contrast, asused herein, the term “hydroohilic” refers to a material having acontact angle of water in air of less than 90 degrees. A CAHN SurfaceForce Analyzer (SFA 222) can be used to measure hydrophilicity, as can avariety of other instruments known in the art.

As used herein, the term “nit” refers to a generally particulatematerial comprising entangled fibers. Nits are sometimes also referredto as “neps,” “fiber bundles” or “fiber flakes.” A nit will alsogenerally comprise capillaries or voids within its structure between theentangled fibers forming the nit and may have an irregular shape, thoughmore regular shapes such as ovoids or spheres can be obtained. Nits willgenerally exhibit a range of sizes resulting in a broad distribution ofpore sizes within a mass of nits, with large pores between the nits andsmaller pores within the nits. This pore size distribution can permitgood intake of viscoelastic materials such as mucous and menses and canprovide good intake of rapid gushes of fluid, while still providing thesmall pores needed for good absorbency and retention of fluid.Generally, nits and other free-flowing particles provide many pores witheffective sizes on the order of the particle size, which generally isgreater than the upper limits of pore size encountered in airlaids,fluff pulp, or tissue.

“Papermaking fibers,” as used herein, include all known cellulosicfibers or fiber mixes comprising cellulosic fibers. Fibers suitable formaking the webs of this invention comprise any natural or syntheticcellulosic fibers from biological sources including, but not limited tononwoody fibers, such as cotton, abaca, kenaf, sabai grass, flax,esparto grass, straw, jute hemp, bagasse, milkweed floss fibers, andpineapple leaf fibers; bacteria capable of producing cellulose; lyocell,rayon, or other men-made cellulose fibers; and woody fibers such asthose obtained from deciduous and coniferous trees, including softwoodfibers, such as northern and southern softwood kraft fibers; hardwoodfibers, such as eucalyptus, maple, birch, and aspen. Woody fibers can beprepared in high-yield or low-yield forms and can be pulped in any knownmethod, including kraft, sulfite, high-yield pulping methods and otherknown pulping methods. In one embodiment, the nits comprise cellulosicfibers from two or more distinct biological sources, such as hardwoodand softwood fibers, or wood-based fibers and cotton, or eucalyptusfibers and hemp fibers, and the like, wherein fibers from each sourcecan be present at a level of 10% or greater based on mass of the fibers,or 20% or greater, or 30% or greater.

Fibers prepared from organosolv pulping methods can also be used.including the fibers and methods disclosed in U.S. Pat. No. 4,793,898,issued Dec. 27, 1988 to Laamanen et al.; U.S. Pat. No. 4,594,130, issuedJun. 10, 1986 to Chang et al.; and U.S. Pat. No. 3,585,104. Usefulfibers can also be produced by anthraquinone pulping, exemplified byU.S. Pat. No. 5,595,628, issued Jan. 21, 1997 to Gordon et al.

In embodiments with bleached papermaking fibers, any known bleachingmethod can be used. Synthetically prepared cellulose fiber can also beused, including rayon in all its varieties and other fibers derived fromviscose or chemically modified cellulose. Chemically treated naturalcellulosic fibers can be used such as mercerized pulps, chemicallystiffened or crosslinked fibers, or sulfonated fibers. In oneembodiment, the fibers are largely unrefined or only lightly refined(e.g., less than 3 hp-days/ton of fiber of applied refining energy).Either recycled fibers or virgin fibers or both can be used, but in oneembodiment the fibers consist essentially of virgin fibers. Mercerizedfibers, regenerated cellulosic fibers, cellulose produced by microbes,rayon, and other cellulosic material or cellulosic derivatives can beused. Suitable papermaking fibers can also include recycled fibers,virgin fibers, or mixes thereof.

As used herein, the term “polymeric web” refers to a porous or nonporouslayer primarily composed of polymeric material, and can be a nonwovenweb, a plastic film, a polymeric film, an apertured film, or a layer offoam. Polymeric webs can be used as wicking barriers, baffle layers,backsheets, and, if sufficiently liquid pervious, as topsheets ofabsorbent articles. A polymeric web can consist of about 50 weightpercent or more polymeric material, more specifically about 80 weightpercent or more polymeric material, and most specifically about 90weight percent or more polymeric material. Exemplary materials includepolyolefins, polyesters, polyvinyl compounds, and polyamides, andcopolymers or mixtures thereof. Many additives and compounds can beadded to the polymeric web or be part of the polymeric components,including anti-bacterial agents, odor-control additives, mineral fillerparticles, surfactants, pigments and dyes, emollients, and the like. Theweb may also be treated to have electrets for improved retention ofcertain particles or components of body fluids.

The term “sanitary napkin”, as used herein, refers to an article whichis worn by females adjacent to the pudendal region that is intended toabsorb and contain the various exudates which are discharged from thebody (e.g., blood, menses, and urine). While the present invention isshown and described in the form of a sanitary napkin, it should beunderstood that the present invention is also applicable to otherfeminine hygiene or catamenial pads such as pantiliners or tampons, orother absorbent articles such as diapers or incontinence pads. The term“feminine care pad” as used herein is synonymous with sanitary napkin.

As used herein, the term “surfactant” includes a single surfactant or amixture of two or more surfactants. If a mixture of two or moresurfactants is employed, the surfactants may be selected from the sameor different classes, provided only that the surfactants present in themixture are compatible with each other. In general, the surfactant canbe any surfactant known in the art, including anionic, cationic,nonionic and amphoteric surfactants. Examples of anionic surfactantsinclude, among others, linear and branched-chain sodiumalkylbenzenesulfonates; linear and branched-chain alkyl sulfates; linearand branched-chain alkyl ethoxy sulfates; and silicone phosphate esters,silicone sulfates, and silicone carboxylates such as those manufacturedby Lambent Technologies, located in Norcross, Ga. Cationic surfactantsinclude, by way of illustration, tallow trimethylammonium chloride and,more generally, silicone amides, silicone amido quaternary amines, andsilicone imidazoline quaternary amines. Examples of nonionicsurfactants, include, again by way of illustration only, alkylpolyethoxylates: polyethoxylated alkylphenols; fatty acid ethanolamides; dimethicone copolyol esters, dimethiconol esters, anddimethicone copolyols such as those manufactured by LambentTechnologies; and complex polymers of ethylene oxide, propylene oxide,and alcohols. One exemplary class of amphoteric surfactants are thesilicone amphoterics manufactured by Lambent Technologies (Norcross,Ga.).

As used herein, “water retention value” (WRV) is a measure that can beused to characterize some fibers useful for purposes of this invention.WRV is measured by dispersing 0.5 gram of fibers in deionized water,soaking overnight, then centrifuging the fibers in a 4.83 cm (1.9 inch)diameter tube with an 0.15 mm (100 mesh) screen at the bottom at 1000gravities for 20 minutes. The samples are weighed, then dried at 105° C.for two hours and then weighed again. WRV is (wet weight—dry weight)/dryweight. Fibers useful for purposes of this invention can have a WRV ofabout 0.7 or greater, more specifically from about 1 to about 2. Highyield pulp fibers typically have a WRV of about 1 or greater.

As used herein, a material will be considered to be “water soluble” whenit substantially dissolves in excess water to form a solution, therebylosing its initial form and becoming essentially molecularly dispersedthroughout the water solution. As a general rule, a water-solublematerial will be free from a substantial degree of crosslinking, ascrosslinking tends to render a material water insoluble. A material thatis “water insoluble” is one that is not water soluble according to theabove definition. Compressed materials in the present invention may bebonded with water soluble materials to permit expansion upon wetting.Water soluble adhesives may be used to join components in the presentinvention. Adhesives and absorbent components may also be water solublein some embodiments.

As used herein, “wet strength agents” are materials used to protect,strengthen, or immobilize the bonds between fibers in the wet state.Typically, the means by which fibers are held together in paper andtissue products involve hydrogen bonds and sometimes combinations ofhydrogen bonds and covalent and/or ionic bonds. In one embodiment of thepresent invention, wet strength additives are used to immobilize thefiber-to-fiber bond points and make them resistant to disruption in thewet state. In this instance, the term “wet state” as used herein refersto a condition when the product is largely saturated with water or otheraqueous solutions, but could also mean significant saturation withwater-containing body fluids such as urine, blood, mucus, menses, runnybowel movement, lymph and other body exudates.

There are a number of materials commonly used in the paper industry toimpart wet strength to paper and board that are applicable to thisinvention. These materials are known in the art as “wet strength agents”and are commercially available from a wide variety of sources. Anymaterial that when added to a paper web or sheet results in providingthe sheet with a mean wet geometric tensile strength:dry geometrictensile strength ratio in excess of 0.1 will, for purposes of thisinvention, be termed a wet strength agent.

Suitable permanent wet strength agents are typically water soluble,cationic oligomeric or polymeric resins that are capable of eithercrosslinking with themselves (homocrosslinking) or with the cellulose orother constituent of the wood fiber. The most widely-used materials forthis purpose are the class of polymer known aspolyamide-polyamine-epichlorohydrin type resins. These materials havebeen described in patents issued to Keim (U.S. Pat. No. 3,700,623 andU.S. Pat. No. 3,772,076) and are sold by Hercules, Inc., located inWilmington, Del., as KYMENE 557H polyamine-epichlorohydrin resins.Related materials are marketed by Henkel Chemical Co., located inCharlotte, N.C., and Georgia-Pacific Resins, Inc., located in Atlanta,Ga. Other useful wet strength agents include thepolyamide-epichlorohydrin resins developed by Monsanto and marketedunder the SANTO RES™ label, including those described in patents issuedto Petrovich (U.S. Pat. No. 3,885,158; U.S. Pat. 3,899,388; U.S. Pat.No. 4,129,528 and U.S. Pat. No. 4,147,586) and van Eenam (U.S. Pat. No.4,222,921). Although they are not as commonly used in consumer products,polyethylenimine resins are also suitable for immobilizing the bondpoints in the products of this invention. Another class ofpermanent-type wet strength agents are exemplified by the aminoplastresins obtained by reaction of formaldehyde with melamine or urea.

The efficacy of cationic wet strength agents can be enhanced bytreatment of cellulosic fibers with reactive anionic compounds,according to U.S. Pat. No. 5,935,383, “Method for Improved Wet StrengthPaper,” issued Aug. 10, 1999 to Tong Sun and J. D. Lindsay, hereinincorporated by reference.

Intake and Rewet Test

The Intake and Rewet test indicates the absorption time to intake 2 mlof synthetic menses simulant. This test method is adapted for nits orother free-flowing particles in an elliptical-shaped nonwoven encasementhaving a major axis of 9.5 cm and a minor axis of 4 cm, comprising 3.0grams of the dry granular material to be tested and a small quantity ofsuperabsorbent particles underneath the granular absorbent material.

The elliptical pouch has a lower surface comprising a 20-gsm SMS(spunbond-meltblown-spunbond laminate) web produced by Corovin GMBH,Germany, treated with 15 gsm of Finley adhesive 2525A on the surface tobe in contact with particles. This 20-gsm web is placed over a dieelement comprising a flat plate with an oval hole in it 9.5 cm long by 4cm wide, with a depth of 9 mm. The 9-mm deep walls of the void in thedie element are vertical. The web sags into the hole. Then 0.5 g ofmicrocrystalline cellulose-coated superabsorbent particles are spreadonto the adhesive of the web in the region over the oval hole of theunderlying plate. The coated superabsorbent particles are prepared fromStockhausen 880 superabsorbent particles (Stockhausen Inc., Greenboro,S.C.) treated with cellulose powder type XL110 from Functional Foods,according to commonly owned copending application Ser. No. 60/129744,“Superabsorbent-containing Composites,” filed Apr. 16, 1999, hereinincorporated by reference. Afterwards, 3.0 grams of dry nits are spreadover the superabsorbent particles such that the depth of the nits overthe 20-gsm SMS layer is substantially uniform in the hole of theunderlying plate. The beds of nits and the SMS layer are covered with a40-gsm spunbond bicomponent (polyethylene/polypropylene) web availableas Prism 12T from Kimberly-Clark Corp. (Neenah, Wis.). The lower SMS andupper bicomponent webs are then heat sealed by bringing a heated elementinto contact with the periphery of the SMS web around the oval hole inthe underlying plate. The two webs are thus thermally joined together todefine an oval-shaped pouch comprising nits and superabsorbentparticles. The pouch is about 6 mm to about 9 mm thick. The pouch isplaced on an hourglass-shaped coform layer 210 mm long and 65 mm wide,consisting essentially of 60 percent polypropylene and 40 percentbleached kraft softwood fibers. The coform is adhesively attached to a20-micron thick polyethylene web serving as a backsheet. A 20-gsmspunbond cover was placed on top of the pouch and coform layer. Thecover stock was attached to the coform and the backsheet with adhesive,and the article was die cut to the same width and length as the coformto form a sanitary napkin. A two millimeter edge seal was embossedwithin the coform and was two millimeters from the edge of the coform.

The pouch of absorbent particles is insulted with 2 ml of processedswine blood (obtained from Cocalico Inc., Reamstown, Pa.) delivered froma fluid reservoir having a 5.04 cm by 1.27 cm rectangular delivery slotcut into a clear acrylic block, such that the slot serves as a well tohold the fluid until it can be absorbed into the absorbent material. Theblock has a mass of 162 g and has a footprint (the contact area againstthe sample) of 7.3 cm by 7.5 cm, with the delivery slot being positionedcentrally within the footprint. The slot is oriented with thelongitudinal direction of the pouch and placed over the longitudinalcenterline thereof. The surface of the block rests flat on the surfaceof the absorbent material, such that intake of fluid occurssubstantially over the area of the slot adjacent the pouch of absorbentmaterial. The time to absorb 2 ml of fluid is measured in seconds usinga stopwatch, based on visual observation. Timing begins when the 2 ml offluid enters the slot and contacts the absorbent material, and timingstops when the fluid has completely passed into the cover or uppersurface of the absorbent material. A lower absorption time is anindication of faster intake rate for the particular material.

Once the material has been insulted, rewet can also be measured. Theplastic block with the slot is left on the material for one minute afterthe fluid is absorbed. After one minute, the block is removed and thematerial is left undisturbed for 8 minutes. Next, preweighed pieces ofFort James (Richmond, Va.) Verigood® brand blotter material are placedon top of the specimen and subjected to a pressure of 3.45 kPa (0.5 psi)for three minutes. After the three minute interval, the blotter paper isremoved and weighed, and the initial weight of the blotter issubtracted, yielding the amount of menstrual fluid absorbed by theblotter paper in grams. Higher values are an indication of a greaterdegree of rewet for the particular material tested.

A total of three rewet and intake measurements are done on eachspecimen.

Method for Determining Centrifuge Retention Capacity

As used herein, the Method for Determining Centrifuge Retention Capacitymeasures the amount of test fluid that a sample of absorbent materialretains after a centrifugal force has been applied. The amount of fluidretained is calculated as a gram per gram retention. The test istypically conducted under TAPPI Standard Conditions.

In general, testing according to this method is performed by placing a0.5 g sample of absorbent material into a modified cylinder, exposingthe sample of absorbent material to a desired fluid for 60 minutes andthen placing the cylinders into a centrifuge to remove excess fluid. Theresults are calculated to obtain the grams of fluid absorbed per gram ofsample of absorbent material.

The following equipment and materials are used in the Method forDetermining Centrifuge Retention Capacity:

-   -   Artificial Menses Fluid (simulant), disclosed in U.S. Pat. No.        5,883,231, issued Mar. 16, 1999, to Achter et al. The simulant        disclosed and claimed in U.S. Pat. No. 5,883,231 is commercially        available from Cocalico Biologicals, Inc. 449 Stevens Rd., P.O.        Box 265, Reamstown, Pa. 17567 USA.    -   Sorvall RT 6000D centrifuge, commercially available from Global        Medical Instrumentation, Inc., 3874 Bridgewater Dr., St. Paul,        Minn. 55123 USA.    -   Four 200 ml, screw top centrifuge bottles, commercially        abailable from International Equipment Co., 300 Second Ave,        Needham Heights, Mass. 02494 USA.    -   Balance, readable to 0.001 g (Note: standards should be NIST        traceable and should be recertified at a frequency adequate to        assure accuracy).    -   Four 50 ml Pyrex beakers.    -   Lab timer, 60 minute capacity, readable to one second,        commercially available from from VWR Scientific Products, 1145        Conwell Ave., Willard, Ohio 44890 USA.    -   Four modified Lexan cylinders, 9 cm high, 3.1 cm ID, 4.8 cm OD,        with a 300 holes/in² screen attached to the bottom.    -   U.S. standard 50 screen sieve, 8 inch diameter, 2 inch height,        commercially available from VRW Scientific Products, 1145        Conwell Ave., Willard, Ohio 44890 USA, catalog number 57334-464.    -   Stainless steel screen, 4 holes per inch or enough open space to        allow simulant to drain.

Specimen Preparation:

Prepare the absorbent material by using the U.S. standard 50 screensieve to fractionate a sample to the 300 to 600 micron size. Store thefractionated sample in a sealed substantially airtight container for usewhen the sample or samples of absorbent material will be prepared. Themodified cylinder is placed on the balance and the weight tared. Then0.5 g of the −30/+50 particle size of the fractionated sample into oneof the modified cylinders. Record this weight as Sample Weight. Themodified cylinder containing the sample of absorbent material is weighedand this weight is recorded as Dry Cylinder Weight. Additional samplesof absorbent material are placed in the three remaining modifiedcylinders according to the foregoing steps.

The simulant is removed from a refrigeration unit, placed on a rotatorand then gently rotated for 30 minutes to thoroughly mix the contentsand bring the simulant to room temperature.

The steps of the testing method are as follows:

-   -   1. 10 ml of simulant are placed into a 50 ml Pyrex beakers.    -   2. A modified cylinder containing the sample of absorbent        material is placed into the 50 ml Pyrex beaker.    -   3. 15 ml of simulant are poured into the modified cylinder. This        ensures that the sample of absorbent material has access to the        simulant from both above and below.    -   4. Repeat steps 2 and 3 as necessary for any desired additional        samples of absorbent material.    -   5. After step 4 has been completed, the timer is set for 60        minutes and started.    -   6. After 60 minutes have elapsed, the modified cylinders are        removed from the Pyrex beakers and placed on the stainless steel        screen for 60 seconds.    -   7. After 60 seconds. the modified cylinders are removed from the        stainless steel screen and placed in the 200 ml centrifuge        bottles.    -   8. The centrifuge bottles are placed in the centrifuge for 3        minutes at 1,200 rpm.    -   9. After 3 minutes, the modified cylinders are removed from the        centrifuge bottles and the modified cylinders containing the        sample of absorbent material is weighed. This weight is recorded        as Wet Cylinder Weight.

The Centrifuge Retention Capacity of each sample of absorbent materialis then calculated according to the following formula:

$\frac{\lbrack {( {{{Wet}\mspace{14mu}{Cylinder}\mspace{14mu}{Weight}} - {{Dry}\mspace{14mu}{Cylinder}\mspace{14mu}{Weight}}} ) - {{Product}\mspace{14mu}{Weight}}} \rbrack}{( {{Product}\mspace{14mu}{Weight}} )}$

Where reported in any of the following examples, the CentrifugeRetention Capacities are an average of two samples (i.e., n=2). Thefree-flowing particles of the present invention can have a CentrifugeRetention Capacity of at least 1.5 g/g, specifically at least 2 g/g, andmost specifically about 2.2 g or greater.

Raw Material Absorbency Rate and Rewet Test Method

As used herein, the Raw Material Absorbency Rate and Rewet Test Methodmeasures at least the following two characteristics of absorbentmaterials:

-   -   1. Absorbency rate—the amount of time, in seconds, it takes for        a known amount of absorbent material to absorb multiple insults        of known quantities of a fluid; and    -   2. Rewet—the amount of fluid, in grams, that is released from        the absorbent material when blotter paper is placed on top of        the absorbent material and a known pressure is applied for a        predetermined period of time.

Testing according to this method consisted of using a stopwatch todetermine the amount of time, in seconds, required for 10 ml ofabsorbent material to absorb multiple insults (1 or 2 ml) of fluid. AHarvard Syringe Pump (Harvard Apparatus, Inc., Holliston, Mass.) isprogrammed to dispense 2 ml of fluid onto 10 ml of absorbent material,at which time a tester simultaneously starts a stopwatch. The stopwatchis stopped when the 2 ml of fluid is absorbed into the absorbentmaterial. A second insult of 2 ml is then dispensed and timed. Thesecond insult is followed by a third insult, this time consisting of 1ml, which is also timed. This results in a total of 5 ml and three timedinsults. The tester then waits 60 seconds from absorption of the thirdinsult before placing a pre-weighed blotter paper onto the 10 ml ofabsorbent material and applying a 0.5 psi pressure for 60 seconds. After60 seconds, the blotter paper is reweighed and the fluid, in grams, thathas been absorbed by the blotter paper is considered the amount ofrewet. Testing is typically conducted under TAPPI Standard Conditions.

Equipment and Materials:

-   -   Harvard Apparatus Programmable Syringe Pump, Model No. 44.        commercially available from Harvard Apparatus, South Natick,        Mass. 01760 USA.    -   The fluid in this instance, by way of example only and not by        way of limitation, is an artificial menses (simulant), disclosed        in U.S. Pat. No. 5,883,231, issued Mar. 16, 1999, to Achter et        al., the disclosure of which is hereby incorporated herein by        reference to the extent that said disclosure is consistent        (i.e., not contradictory) with the present specification. The        simulant disclosed and claimed in U.S. Pat. No. 5,883,231 is        commercially available from Cocalico Biologicals, Inc., 449        Stevens Rd., P.O. Box 265, Reamstown, Pa. 17567 USA.    -   Disposable plastic weighing boats commercially available from        NCL of Wisconsin, Inc., Birnamwood, Wis. 54414 USA, part number        W-D 80055.    -   60 cc disposable syringe, commercially available from Becton        Dickenson, Rutherford, N.Y. USA; Tygon tubing, size 16 with        0.12″ inner diameter, part number 6409-16, commercially        available from Cole-Parmer Instrument Company, Chicago, Ill.        60648 USA; and ⅛″ outer diameter hose, barb size, pact number        R-3603 and also commercially available from Cole-Parmer        Instrument Company.    -   5.5 cm blotter paper, commercially available from from VWR        Scientific Products, 1145 Conwell Ave., Willard, Ohio 44890 USA,        catalog number 28310-015.    -   Weight, made by taking a 100 ml Pyrex beaker and filling it with        any suitable substance to 717.5 grams to obtain a 0.5 psi        loading.    -   Balance, readable to 0.001 g (Note: standards should be NIST        traceable and should be recertified at a frequency adequate to        assure accuracy).    -   Stopwatch, readable to 0.1 s (Note: stopwatch should be NIST        traceable).    -   Graduated cylinder readable to 20 ml.    -   Clear acrylic plate (of a size sufficient to be supported on top        of a disposable plastic weighing boat) with a hole drilled in        the center thereof for insertion of the Tygon tubing.

Specimen Preparation:

The simulant is removed from a refrigeration unit, placed on a rotatorand then gently rotated for 30 minutes to thoroughly mix the contentsand bring the simulant to room temperature.

The graduated cylinder is placed onto the balance and the weight tared.10 ml of absorbent material is introduced into the graduated cylinder.The graduated cylinder is removed from the balance. The bottom of thegraduated cylinder is gently tapped on the top of the lab bench orsimilar hardened surface 10 times to induce settling. Visual inspectionis made to ensure that there is 10 ml of absorbent material in thegraduated cylinder. The 10 ml of absorbent material is poured into aweighing boat and the absorbent material is gently leveled.

The Harvard Syringe Pump is set to the Program Mode. The Infuse Rate isset to 250 ml/hr. with the Target Volume set to 2 ml. Diameter is set tothe correct syringe size. The Harvard Syringe Pump is filled with 60 mlof simulant.

The steps of the testing method are as follows:

-   -   1. One end of the Tygon tubing is inserted through the hole in        the acrylic plate.    -   2. The acrylic plate is placed over a weighing boat containing        10 ml of absorbent material. The Tygon tubing should be centered        over the center of the absorbent material.    -   3. Simultaneously start the stopwatch and begin dispensing the        first 2 ml insult of simulant.    -   4. Stop the stopwatch when the simulant is absorbed by the        absorbent material. The reading on the stopwatch is recorded as        “Insult 1” in seconds. In the event that the simulant is not        absorbed by the absorbent material being tested (i.e., the        simulant sits on the top of the absorbent material) within five        minutes, stop the test and record 300+ seconds.    -   5. Simultaneously start the stopwatch and begin dispensing the        second 2 ml insult of simulant.    -   6. Stop the stopwatch when the simulant is absorbed by the        absorbent material. The reading on the stopwatch is recorded as        “Insult 2” in seconds. In the event that the simulant is not        absorbed by the absorbent material being tested (i.e., the        simulant sits on the top of the absorbent material) within five        minutes, stop the test and record 300+ seconds.    -   7. Simultaneously start the stopwatch and begin dispensing the        simulant. In this instance, however, the Harvard Syringe Pump is        halted after 1 ml of simulant has been dispensed.    -   8. Stop the stopwatch when the 1 ml of simulant is absorbed by        the absorbent material. The reading on the stop watch is        recorded as “Insult 3” in seconds. Once again, should the        simulant not be absorbed by the absorbent material being tested        (i.e., the simulant sits on the top of the absorbent material)        within five minutes, stop the test and record 300+ seconds.    -   9. Wait 60 seconds after adsorption of the third insult.    -   10. Weigh two pieces of blotter paper and record this weight as        “BP Dry.”    -   11. At the end of the 60 seconds noted in step 9, gently place        the 0.5 psi weight onto the blotter paper and start the        stopwatch.    -   12. After 60 seconds, remove the weight and reweigh the blotter        paper. This weight of the blotter paper is recorded as “BP Wet.”

Steps 3 through 12 outlined above are repeated until the simulant is nolonger absorbed by the absorbent material (i.e., the simulant sits onthe top of the absorbent material and is not absorbed within fiveminutes).

The results of the rewet portion of the test method are recorded ingrams and calculated as follows:(BP Wet)−(BP Dry)=Rewet

Angle of Repose Test

As used herein, “angle of repose” refers to the angle relative to thehorizontal plane formed by the sides of a pile of free flowing particlesprepared under controlled circumstances. Generally, a low angle ofrepose is indicative of the ability to flow readily, while a high angleof repose suggests that particulates do not flow well or tend to adhere.A measurement for angle of repose suited for the free-lowing particlesof the present invention will be described using FIGS. 9 and 10. FIG. 9depicts an apparatus 100 intended to permit measurement of the angle ofrepose of a pile of particles formed on a cylindrical platform 110. Theapparatus comprises a powder funnel 102 (a Nalgene® 80 mm plasticfunnel, Catalog No. 30252-955 in the VWR Scientific Products Catalog)having a height of 106 mm (the distance from the top of the funnel tothe top of the stem 108). The powder funnel 102 has an upper opening 104that is 104 mm wide. The lower stem 108 that has an outer diameter of 21mm, a length of 33 mm, and is provided with a lower opening 106.Particles placed in the funnel fall to the brass cylinder 110 having adiameter D of 15.2 cm. The edges are free of burrs or othernonuniformities that would prevent particles from falling off thecylinder. The cylinder 110 is axially centered with the axis of thefunnel 102. The upper surface of the cylinder 110 resides a distance Lof 15 cm below the lower opening 106 of the funnel 102. The cylinder 110has a height great enough to permit particles to spill to the sidewithout rising from the underlying platform to reach the level of theupper surface of the cylinder 110. A height of at least 5 cm isrecommended. The powder funnel 102 is held with a ringstand. Both thefunnel 102 and the cylindrical platform 110 should be leveled.

To conduct the test, 100 cubic centimeters of particles are poured intothe funnel 102. The particles are allowed to fall under the force ofgravity to form a pile on the cylinder below, as shown in FIG. 10. Theheight H of the particle pile 120 on the cylinder 110 is measured,relative to the plane of the upper surface of the cylinder 110. Theangle of repose, θ_(r), for the particles is then given by the arctangent of H/R, where R is the radius of the cylinder 110 (D/2). Thismeasurement is repeated 5 times to yield an average.

The effect of moisture should be considered in measuring angle ofrepose. Unless otherwise stated, it is assumed that the angle of reposeis measured for substantially dry particles in equilibrium with air at23° C. with a relative humidity of 30%, which typically will result inmoisture content less than 5% for cellulosic nits. The effect ofincreasing moisture on the nits can be observed by measuring angle ofrepose as the nits are brought to increasing levels of moisture content.Conditioning the nits at a relative humidity of about 50%, for example,can bring the nits to a moisture content of about 5 to 7% in most cases,and higher relative humidities can be used to further elevate moisturecontent. For moisture contents above about 10%, it may be necessary toapply a fine mist of deionized water to the nits as they are stirred andto allow 15 minutes for a uniform redistribution of moisture within thenits. Once moistened, the nits are again measured for angle of repose.

If particles begin to bridge and cease flowing freely from the funnel,gentle tapping may be performed by gently striking the outer surface ofthe funnel three times at three uniformly spaced locations about thediameter of the funnel 102 at a height of 10 cm above the lower outlet106, spaced apart by about 0.5 seconds. Striking is performed with onlyenough force to dislodge the particles. If bridging continues to be aproblem, the particles can be slowly trickled into the funnel 102 toallow them to fall through the stem 108 and onto the cylindricalplatform 110.

Nits without debonder and nits with a substantial amount of loose fibersprojecting from the surface of the nits will often have an angle ofrepose as high as about 70 degrees when dry, but can still be useful inthe present invention. When a greater degree of flowability is desired,free-flowing particles useful in the present invention can have an angleof repose while dry of about 60 degrees or less, more specifically about55 degrees of less, and most specifically about 47 degrees or less, withexemplary ranges of from 10 to 45 degrees or from about 25 degrees toabout 38 degrees. In some embodiments, at a moisture content of 50% (50grams of water per 100 grams of dry fiber) and even 100%, the particleswill still have an angle of repose less than about 75 degrees and canstill be within the ranges specified above for dry particles. The angleof repose can increase by no more than 15 degrees, specifically no morethan 10 degrees, and most specifically no more than 6 degrees, asmoisture content is increased from 5% to 100%.

Gel Bed Permeability (GBP) Test

A suitable piston/cylinder apparatus for performing the Gel BedPermeability (GBP) test is shown in FIGS. 11 and 12. Referring to FIG.11, apparatus 420 consists of a cylinder 422 and a piston generallyindicated as 424. As shown in FIG. 11, piston 424 consists of acylindrical LEXAN® shaft 426 having a concentric cylindrical hole 428bored down the longitudinal axis of the shaft. Both ends of shaft 426are machined to provide ends 430 and 432. A weight, indicated as 434,rests on end 430 and has a cylindrical hole 436 bored through the centerthereof. Inserted on the other end 432 is a circular piston head 440.Piston head 440 is sized so as to vertically move inside cylinder 422.As shown in FIG. 12, piston head 440 is provided with inner and outerconcentric rings containing seven and fourteen 0.95 cm (0.375 inch)cylindrical holes, respectively, indicated generally by arrows 442 and444. The holes in each of these concentric rings are bored from the topto bottom of piston head 440. Piston head 440 also has cylindrical hole446 bored in the center thereof to receive end 432 of shaft 426.

Attached to the bottom end of cylinder 422 is a No. 400 mesh stainlesssteel cloth screen 448 that is biaxially stretched to tautness prior toattachment. Attached to the bottom end of piston head 440 is a No. 400mesh stainless steel cloth screen 450 that is biaxially stretched totautness prior to attachment. A sample of absorbent material indicatedas 452 is supported on screen 448.

Cylinder 422 is bored from a transparent LEXAN® rod or equivalent andhas an inner diameter of 6.00 cm (area=28.27 cm²), a wall thickness of0.5 cm, and a height of 5.0 cm. Piston head 440 is machined from aLEXAN® rod. It has a height of 0.625 inches (1.59 cm) and a diametersized such that it fits within cylinder 422 with minimum wallclearances, but still slides freely. Hole 446 in the center of thepiston head 440 has a threaded 0.625 inch (1.59 cm) opening (18threads/inch) for end 432 of shaft 426. Shaft 426 is machined from aLEXAN® rod and has an outer diameter of 0.875 inches (2.22 cm) and aninner diameter of 0.250 inches (0.64 cm). End 432 is 0.5 inches (1.27cm) long and is threaded to match hole 446 in piston head 440. End 430is 2.54 cm (1 inch) long and 1.58 cm (0.623 inches) in diameter, formingan annular shoulder to support the stainless steel weight 434. Theannular stainless steel weight 434 has an inner diameter of 1.59 cm(0.625 inches), so that it slips onto end 430 of shaft 426 and rests onthe annular shoulder formed therein. The combined weight of piston 424and weight 434 equals 596 g, which corresponds to a pressure of 20,685dynes/cm² (0.30 psi), for an area of 28.27 cm².

When solutions flow through the piston/cylinder apparatus, the cylinder422 generally rests on a 16-mesh, rigid stainless-steel support screen(not shown) or equivalent.

The piston and weight are placed in an empty cylinder to obtain ameasurement from the bottom of the weight to the top of the cylinder.This measurement is taken using a caliper readable to 0.01 mm. Thismeasurement will later be used to calculate the height of the gel bed.It is important to measure each cylinder empty and keep track of whichpiston and weight were used. The same piston and weight should be usedfor measurement when gel is swollen.

The adsorbent layer used for GBP measurements is formed by swelling 3.0g of a absorbent material in the GBP cylinder apparatus (dry polymershould be spread evenly over the screen of the cylinder prior toswelling) with 0.9% (w/v) aqueous NaCl for a time period of 15 minutes.The sample is taken from a population of absorbent material that isprescreened through U.S. standard #30 mesh and retained on U.S. standard#50 mesh. The absorbent material, therefore, has a particle size ofbetween 300 and 600 microns. The particles may be prescreened by hand orautomatically prescreened with, for example, a Ro-Tap Mechanical SieveShaker Model B, commercially available from W. S. Tyler, Inc., Mentor,Ohio USA.

At the end of the period, the cylinder is removed from the fluid andpiston weight assembly is placed on the gel layer. The thickness of theswollen layer is determined by measuring from the bottom of the weightto top of the cylinder with a micrometer. The value obtained when takingthis measurement with the empty cylinder is subtracted from the valueobtained after swelling the gel. The resulting value is the height ofthe gel bed H.

The GBP measurement is initiated by adding the NaCl solution to cylinder422 until the solution attains a height of 4.0 cm above the bottom ofthe gel layer 452. This solution height is maintained throughout thetest. The quantity of fluid passing through the gel layer 452 versustime is measured gravimetrically. Data points are collected every secondfor the first two minutes of the test and every two seconds for theremainder. When the data are plotted as quantity of fluid passingthrough the bed versus time, it becomes clear to one skilled in the artwhen a steady flow rate has been attained. Only data collected once theflow rate has become steady is used in the flow rate calculation. Theflow rate, Q, through the gel layer 452, is determined in units of g/secby a linear least-square fit of fluid passing through the gel layer(measured in grams) versus time (in seconds).

Permeability in cm² is obtained by the following equation:K=[Q*(H*Mu)]/[A*Rho*P]where K=Gel Bed Permeability (cm²); Q=flow rate (g/sec); H=height of gelbed (cm); Mu=liquid viscosity (poise); A=cross-sectional area for liquidflow (cm²); Rho=liquid density (g/cm³); and P=hydrostatic pressure(dynes/cm²) (normally 3923 dynes/cm²).

AUL and Free-swell Tests

“Absorbency Under Load” (AUL) is a measure of the liquid retentioncapacity of a material under a mechanical load. It is determined by atest which measures the amount in grams of an aqueous solution,containing 0.9 weight percent sodium chloride, a gram of a material canabsorb in 1 hour under an applied load or restraining force of about 2kPa (0.3 pound per square inch).

The AUL apparatus comprises a Demand Absorbency Tester (DAT) asdescribed in U.S. Pat. No. 5,147,343, issued Sep. 15, 1992 toKellenberger, herein incorporated by reference, which is similar to aGATS (Gravimetric Absorbency Test System), available from M/K Systems,Danners, Mass. A level porous plate is used having ports confined withina 2.5 cm. diameter area to provide liquid saline solution, 0.9 (w/w) %sodium chloride, delivered from a reservoir to the porous plate suchthat there is no hydraulic head (neither positive pressure nor suction)at the top of the porous plate. Thus, fluid can be absorbed into theabsorbent without overcoming a significant capillary pressure barrier tomove liquid out of the porous plate. Fluid absorbed from the plate isreplaced with liquid from the reservoir, which resides on an electronicbalance that measures the amount of liquid removed from the reservoirand absorbed into the absorbent. The sample on the porous plate resideswithin a section of 2.54 cm (one-inch) inside diameter thermoplastictubing machined-out slightly to be sure of concentricity. Stainlesssteel wire cloth with 0.15 mm openings (100 mesh) is fused on the bottomof the cylinder to restrain the sample and any particulates therein.Care must be taken to maintain a flat smooth bottom and not distort theinside of the cylinder. A 4.4 g piston (“spacer disk”) is made from 2.54cm (one inch) diameter solid material (e.g., a clear plastic) and ismachined to closely fit without binding in the cylinder (i.e., thediameter is reduced to 2.527 cm). A standard 100 gm weight placed on thepiston is used to provide a 21,000 dyne/sq.cm. (about 0.3 psi)restraining load which is commonly experienced in infant diapers. Tocarry out the test with a foam-like fibrous material or a foam, amaterial sample is cut into circular discs with a diameter slightlysmaller than 2.54 cm (one inch) to freely fit within the sample tube.The sample mass should be from about 0.05 g to about 0.16 g.

This test is initiated by placing a 3 cm diameter GF/A glass filterpaper onto the porous plate (the paper is sized to be larger than theinner diameter and smaller than the outer diameter of the cylinder), toinsure good contact while eliminating evaporation over the ports of theDAT and then allowing saturation to occur. The material to be tested isplaced on the wire cloth at the bottom of the AUL apparatus. The sampleis then covered with the plastic spacer disc, which serves to protectthe sample from being disturbed during the test and also to uniformlyapply a load on the entire sample. After carefully placing the pistonand weight on the sample in the cylinder, the AUL apparatus is placed onthe glass filter paper. The amount of fluid pick-up is monitored as afunction of time either directly by hand, with a strip chart recorder ordirectly into a data acquisition system.

The amount of fluid pickup measured after one hour is the AUL value,expressed as grams of liquid per dry gram of the tested material.

The AUL of the materials of the present invention can be above 6grams/gram, more specifically about 10 grams/gram or greater, still morespecifically about 15 grams/gram or greater, and most specifically about25 grams/gram or greater, with an exemplary range of from about 9 toabout 40 grams/gram. While high AUL values can be achieved without theaddition of superabsorbent material or swellable binder material,especially high values of AUL are possible through incorporation ofsuperabsorbent material into the absorbent structure.

As used herein, “Free Swell Capacity” (FS) is the result of a test whichmeasures the amount in grams of an aqueous solution, containing 0.9weight percent sodium chloride, that a gram of a material can absorb in1 hour under negligible applied load. The test is done as describedabove for the AUL test, except that the 100 gm weight is not placed onthe sample.

The Free Swell Capacity of the materials of the present invention can beabove 8, more specifically above 10, more specifically above 20, andmost specifically above 30 grams/gram.

As used herein, “Free Swell:AUL Ratio” is the ratio of Free SwellCapacity to AUL. It will generally be greater than one. The higher thevalue, the more sensitive the material is to compressive load, meaningthat the sample is less able to maintain its potential pore volume andcapillary suction potential under load. The materials of the presentinvention have “Free Swell:AUL Ratio” of about 4 or less, morespecifically about 2 or less, more specifically still about 1.5 or less,and more specifically about 1.3 or less with an exemplary range of fromabout 1.2 to about 2.5.

DETAILED DESCRIPTION OF THE DRAWINGS

It has been discovered that excellent fluid intake and controlproperties can be achieved in an absorbent article through the use offree-flowing absorbent particulates such as loose fibrous “nits”contained within an absorbent article. Synergistic benefits in fluidhandling and body fit can be obtained when a pouch of free-flowingparticles is coupled with other elements in an absorbent article. Forexample, good results have been obtained with cellulosic fibrous nitscomprising papermaking fibers which have been mechanically formed bydisperging to entangle fibers into small, discrete bundles.

Preparation of Nits

Some basic aspects of nit preparation are disclosed in U.S. Pat. No.5,800,417, “Absorbent Composition Comprising Hydrogel-Forming PolymericMaterial and Fiber Bundles,” issued to K. Goerg-Wood et al., Sep. 18,1998, herein incorporated by reference in its entirety.

One embodiment of a production process according to the presentinvention is illustrated in general in the flow chart of FIG. 1. Moistfibers are first provided, typically at an elevated consistencytypically greater than 10% and more specifically at about 20% or higherand most specifically at about 30% or higher with an exemplary range of32% to about 55%. Any papermaking fibers can be used, as well as othercellulosic or absorbent polymer fibers capable of forming nits. In oneembodiment, hardwood fibers are the primary fibrous component of thenits. In a related embodiment, short papermaking fibers are used for theproduction of nits, wherein the fibers have a weight-average length ofless than 3.5 mm, specifically less than about 2 mm, and morespecifically from about 0.2 mm to about 1.7 mm based on fiber lengthmeasurement with a Kajaani FS-200 instrument.

Providing the fibers at elevated consistency can require a dewateringstep to make dilute fiber suspensions more concentrated. For example, alow-consistency slurry can be dewatered in a belt press. The belt presscan be any suitable commercially-available unit. such as a Belt FilterPress from Komline Sanderson (Peapack, N.J.). Depending on the volume ofmaterial being processed, several belt presses may be arranged inparallel to provide the desired capacity. Process white water from thebelt press can be conducted back to the pulping unit or other portionsof the mill requiring water. At the outlet of the belt press, the filtercake typically can have from 25-45% solids, more specifically 30 to 45%solids and most specifically 35-40% solids. Other dewatering means forelevating the consistency of dilute fiber slurries include centrifugalfiltration, screw presses, filtration and pressing on a papermakingmachine, screen filters, flash drying, evaporative drying, and the like.

As shown in FIG. 1, mechanical energy is applied to the fibers duringthe disperging process of the present invention to cause fiberentanglement. A single- or twin-shaft disperger can be used capable ofapplying high-shear to pulp. High-shear treatment can last for about oneminute or more (i.e., the average retention time of fibers passingthrough the device can be about one minute or greater). Examples ofspecific devices suitable for disperging include the BIVIS machine(commercially available from Clextral Company, Firminy Cedex, France)and the Maule shaft disperger such as Maule Type GR 11 manufactured byIng. S. Maule & C. S.p.A., Torino, Italy, illustrated and described indetail in U.S. Pat. No. 5,772,845, “Soft Tissue,” issued Jun. 30, 1998to Farrington, Jr. et al., herein incorporated by reference.

Also of use in the present invention are other known dispergers forhigh-consistency treatment of papermaking pulp, such as those describedby David W. Hostetter in “Comparing Kneading and Disk Dispersion,”PaperAge, November 1995, p. 16. Hostetter explains that typical diskdispergers and kneaders for papermaking applications work by shearingaction at around 30% consistency, with power requirements typically from60 to 90 kWh/ton. Disk dispersion (or disperging) is generally mosteffective at 95° C. or higher, so disk dispergers are often preceded bya heating unit such as a heated screw conveyor. They operate typicallyat 1200 to 1800 rpm. One example is the Voith Sulzer “HTD” disperger(Appleton, Wis.), which has automatic power control and control over thegap where much of the shear on the fibers takes place. For best results.disk dispergers generally should be operated at low throughputs toincrease the dwell time and energy applied to the fibers in order topromote nit formation. When exposure to high shear is for a short periodof time, an additional disperging step may be needed to create suitablenits.

Kneaders (regarded as a specific form of disperger as used herein)usually operate at lower temperatures, such as about 40° C. to 70° C.,and are available in single and double shaft designs with rotationalspeeds of 200 to 1000 rpm. Retention time in the kneading zone is longcompared to disk dispersion and can be effective in imparting curl orentanglement. One example of a kneader is the Voith Sulzer KD-500kneading disperger (so termed in the above-referenced article ofHostetter—kneading can be considered as one form of disperging for thepurposes of the present invention). The Ahlstrom MDR® Kneader can alsobe used. Another example of a kneader is provided in U.S. Pat. No.3,836,336, issued Sep. 17, 1974 to Yasui et al., herein incorporated byreference. Kneaders are generally operated at power levels similar tothose of disk dispergers or other dispergers, but can be operated athigher power levels for purposes of the present invention.

All forms of dispergers in prior commercial operation, includingkneaders, disk dispergers, and shaft dispergers, are believed to havegenerally been run in a manner to avoid the formation of nits, which arenot desired for commercial paper production. However, for the purposesof the present invention, nit formation is to be promoted by operation,for example, at one or more of elevated energy levels, elevated dwelltimes (tied to throughput), and elevated consistencies. For a givendevice, simple optimization of energy, throughput, and consistency canbe applied to maximize nit production. Further, applied power,throughput rates, and temperature can be optimized for a given furnishto achieve the targeted particle density, absorbent capacity, and sizedistribution. Chemical additives (nit conditioners) can also play auseful but optional role, as described below. In one embodiment, energylevels above the typical levels of commercial disperger operation areapplied. Specifically, energy levels above 90 kilowatt-hours/ton (kwh/t)can be applied. More specifically, energy levels for disperging offibers can be any of the following ranges: about 95 kwh/t or greater,about 140 kwh/t or greater, about 200 kwh/t or greater, from about 95kwh/ton to about 600 kwh/t, and from about 110 kwh/ton to about 300kwh/ton.

In the BIVIS disperger, consistencies greater than 50% can be utilizedwithout plugging. This device can be generally described as apressurized twin screw shaft disperger, each shaft having several screwflights oriented in the direction of material flow followed by severalflights oriented in the opposite direction to create back pressure. Thescrew flights are notched to permit the material to pass through thenotches from one series of flights to another. One can utilize aconsistency which is as high as possible for the particular machine usedin order to maximize fiber-to-fiber contact, or can optimize theconsistency for the particular product attributes being sought.

The temperature of the fibrous suspension entering the disperger can beabout 20° C. or greater, specifically about 50° C. or greater, morespecifically about 70° C. or greater, and most specifically about 90° C.or greater. Disperging (generally synonymous with “dispersing” or“dispersion” in the art of mechanical treatment of papermaking fibers)will elevate the temperature, depending on the energy input. Thetemperature of the pulp immediately after dispersion can be about 50° C.or higher, more specifically about 80° C. or higher, with an exemplaryrange of 90° C. to 130° C. and more specifically from about 100° C. toabout 115° C. The upper limit on the temperature is dictated by whetheror not the apparatus is pressurized, since the aqueous fibroussuspensions within an apparatus operating at atmospheric pressure cannotbe heated beyond the boiling point of water. Other principles foroperation of dispergers are disclosed in U.S. Pat. No. 5,348,620,“Method of Treating Papermaking Fibers for Making Tissue,” issued toHermans et al., Sep. 20, 1994, and those parts of which that are notcontradictory to the present invention are herein incorporated byreference.

The outlet consistency from the disperger (e.g., a BIVIS or Mauledevice) can be from about 20% to about 75%, specifically from about 40%to about 60% and more specifically from about 45% to about 55%. Goodresults can be obtained with specific energy values above about 90kilowatt hours per metric ton, though it is expected that some nits canbe produced at energy input levels as low as 25 to 90 kilowatt-hours permetric ton and also at much higher specific energy levels, such as about300 or 600 kilowatt-hours per metric ton. Outlet consistency in practicehas ranged from 47% to 55%, though lower and higher values are withinthe scope of the present invention, as previously defined.

Nit Conditioners and Particle Conditioners

As shown in the embodiment of FIG. 1, the nits (as well as otherfree-flowing particles) can be treated at least in part with nitconditioners (or, more generally, “particle conditioners”) such as adebonder, a lubricant, a wax, a silicone compound, or other hydrophobicmaterial to modify fiber-fiber interactions during disperging and/or tomodify particle-particle interactions once incorporated into anabsorbent article. For example, nit conditioners or particleconditioners can improve the free flowing properties of the particles.Such conditioners and other chemicals can be added at any suitable timeduring preparation and treatment of the particles. In the case of nits,nit conditioners can be added in a pulper as pulp is initially beingdisintegrated and prepared, during or after a dewatering process whereinpulp consistency is being elevated, at the inlet of the disperger (e.g.,at a feed screw), or nit conditioners and other chemicals can beinjected into any one of several zones in the disperger itself or addedto the nits after formation, such as before, during, or after drying.Also, chemical addition during or after nit drying can be selectivelyonto the surface of the surface and can efficiently modifyparticle-particle interactions.

Surprisingly, addition of debonder or lubricants prior to or duringpreparation of fibrous nits from moist fibers has been discovered toreduce the particle size distribution of the nits and can increase theyield of nits in a desired particle size range. In addition to thebenefits obtained by adding debonders known from the art of papermaking,benefits in nit properties can also be achieved by adding knownsurfactants or dispersants during the processing of the nits. Withoutwishing to be bound by theory, it is believed that lubricants such aswaxes, oils, and silicone compounds, or surfactants or dispersants, suchas Triton X-100, when present during a disperging operation, can modifythe surface interactions between fibers to reduce the size of nitsformed from entangled fibers. It is also believed, again without wishingto be bound by theory, that the presence of an effective amount of atleast one of lubricants, debonders, dispersants and surfactants duringhigh-consistency disperging of papermaking fibers can reduce thefriction between nits and allow nits to flow past one another morereadily, permitting local velocity fields or shear fields to beestablished that better promote separation of nits and creation of nitswith reduced-quantities of fibers projecting from the surface of thenits.

Without wishing to be bound by theory, it is believed that debonders onthe surface of a fibrous nit can prevent bonding or clumping betweennits and can enhance the lubricity of the nits relative to one another.Thus, it is believed that debonder selectively located on the outersurface of a nit will be more effective in terms of the performance ofan absorbent article than debonder applied uniformly throughout thefibrous material of a nit. However, in the manufacturing of nits, it hasbeen found that debonder present throughout the pulp often improves thesize distribution of the nits by reducing the size of the nits into adesired range. Again, without wishing to be bound by theory, it isbelieved that the presence of debonder increases the lubricity of fibersduring a disperging process and allows flocs to be broken up intosmaller sized bundles. Thus, for example, a process that might result ina mean particle size of about 1 mm without debonder might yield a meanparticle size of about 0.6 mm with 0.5% to 2% debonder present (weightpercentage based on dry fiber mass).

Application of the debonding agent can therefore be done in either orboth of two ways: (1) applying a debonder to the fibers or fiber slurryprior to or during disperging to control formation of nits and nit size,and (2) applying a debonder (or other hydrophobic material or compoundcomprising fatty moieties) to the surface of at least a portion of thenits after the nits have been formed by mechanical processes and before.after, or during drying of the nits.

Many debonders tend to reduce water absorbency as a result ofhydrophobicity caused by the same fatty long chain portion which givesthe product its effectiveness. In order to overcome this problem, somemanufacturers have formed adducts of ethylene or propylene oxide inorder to make the products somewhat more hydrophilic. Those interestedin the chemistry of debonders will find them widely described in thepatent literature. The following list of U.S. patents provides asampling, although it is not intended to be exhaustive: Hervey et al.,U.S. Pat. Nos. 3,395,708 and 3,554,862; Forssblad et al, U.S. Pat. No.3,677,886; Emanuelsson et al., U.S. Pat. No. 4,144,122; Osborne, Ill.,U.S. Pat. No. 4,351,699; and Helisten et al., U.S. Pat. No. 4, 476,323.All of the aforementioned patents describe cationic debonders. Laursen,in U.S. Pat. No. 4,303,471, herein incorporated by reference, describeswhat might be considered a representative nonanionic debonder.

Suitable debonders include any number of quaternary ammonium compoundsand other softeners known in the art, including Berocell 596 and 584(quaternary ammonium compounds) manufactured by Eka Nobel Inc., whichare believed to be made in accordance with U.S. Pat. Nos. 3,972,855 and4,144,122; Adogen 442 (dimethyl dihydrogenated tallow ammonium chloride)manufactured by Sherex Chemical Company; Quasoft 203 (quaternaryammonium salt) manufactured by Quaker Chemical Company; and Arquad 2HT75(di(hydrogenated tallow) dimethyl ammonium chloride) manufactured byAkzo Chemical Company. Softening agents known in the art of tissuemaking can also serve as debonders or hydrophobic matter suitable forthe present invention and can include, without limitation, fatty acids,waxes, quaternary ammonium salts, dimethyl dihydrogenated tallowammonium chloride, quaternary ammonium methyl sulfate, carboxylatedpolyethylene, cocamide diethanol amine, coco betaine, sodium lauroylsarcosinate, partly ethoxylated quaternary ammonium salt, distearyldimethyl ammonium chloride, methyl-1-oleyl amidoethyl-2-oleylimidazolinium methylsulfate (Varisoft 3690 from Witco Corporation), andthe like.

Anti-static agents typically have side chains similar to those of usefuldebonders and can be present as well. In some cases, anti-staticcompounds are helpful in reducing static electricity-induced clumping ofnits in their dry state, especially during manufacturing.

Silicone compounds can be useful in providing nits with desiredproperties, especially in terms of resisting clumping when wet and inproviding useful tactile and free flowing properties when dry. Usefulsilicone compounds include silicone-based debonders, anti-static agents,softness agents, surface active agents, and the like, many of which canbe obtained from Lambent Technologies, Inc., as described by A. J.O'Lenick, Jr., and J. K. Parkinson, in “Silicone Compounds: Not Just OilPhases Anymore,” Soap/Cosmetics/Chemical Specialties, Vol. 74, No. 6,June 1998, pp. 55-57. Exemplary silicone compounds include siliconequats such as silicone alkylamido quaternary compounds based ondimethicone copolyol chemistry, which can be useful as softeners,anti-static agents, and debonders; silicone esters, including phosphateesters which can provide lubricity; dimethiconol stearate anddimethicone copolyol isostearate, which is highly lubricious and can beapplied as microemulsion in water; silicone copolymers withpolyacrylate, polyacrylamide, or polysulfonic acid; siliconeiethioniates; silicone carboxylates; silicone sulfates; siliconesulfosuccinates; silicone amphoterics; silicone betaines; and siliconeimidazoline quats. Related patents describing such compounds includingthe following: U.S. Pat. Nos. 5,149,765; 4,960,845; 5,296,434;4,717,498; 5,098,979; 5,135,294; 5,196,499; 5,073,619; 4,654,161;5,237,035; 5,070,171; 5,070,168; 5,280,099; 5,300,666;:4,482,429;4,432,833 (which discloses hydrophilic quaternary amine debonders) andU.S. Pat. No. 5,120,812, all of which are herein incorporated byreference. Hydrophilic debonders may be applied at the same doses and ina similar manner as hydrophobic debonders.

Though chemical additives that serve as debonders or lubricants can beuseful in the production of nits for one or more of prevention ofagglomeration, reduction of particle cohesiveness, prevention of staticelectricity (in the case of some cationic debonders in particular), andgood control over nit size during disperging, nevertheless, othersurface-active compounds can also play a role in controlling nitformation during disperging. Thus, a variety of surfactants anddispersants (previously defined) known in the art can also be appliedduring disperging to modify fiber-fiber interactions, modify nit-nitinteractions, or control flocculation tendencies in the pulp suspension,all with potential benefits in controlling nit size or rheology of thedry particles.

Surfactants can be anionic, cationic, or nonionic, and can include anyknown in the art that are not incompatible with the health and propertyrequirements of the present invention.

The nits can be combined with other agents in the pouch to furtherincrease the absorbent capacity of the pouch or to control fluid thehandling performance or macroscopic mechanical or rheological propertiesof the contents of the pouch. Materials capable of providing additionalabsorbent capacity include superabsorbent particles, particularlysuperabsorbents adapted for intake of menses, cellulose fibers.superabsorbent fibers and films, and one or more layers of asuperabsorbent-treated tissue. The nits can also comprise a percentageof inorganic material or minerals such as clays (e.g., kaolin clay,bentonite, etc.), calcium carbonate, zeolites, vermiculite, titaniumdioxide, mica, talc, alumina, silica, sodium bicarbonate, and the like.Other additives can be applied for specific purposes, such as odorcontrol agents, ion exchange resins, anti-microbials, chitosan andchitin particles or additives, enzymes, surfactants. plasticizers suchas polyols, and the like. Add-on levels can be varied to achieve thedesired objectives, but by way of example can be selected from any ofthe following ranges for weight percents based on dry fibers: from 1% to50%, from 2% to 10%, from 1%-5%, less than 10%, less than about 5%, lessthan 2%, from about 0.2% to about 3%, and substantially 0%.

For polymethyl urea spheres or for free-flowing particles in general,Vermiculite and clay particles can be present, particularly when othermore regular shaped particles are present to enhance flowability. Forexample, if about 20% or more, specifically about 30% or more and morespecifically about 40% or more of the volume of the particulate matteris occupied by substantially spherical or ovoid free-flowing particles,non-spherical particles such as vermiculite or clays can be presentwhile still permitting good rheological properties to be maintained.Likewise, when over 40% and specifically over 50% of the mass ofparticulate matter is nits, then clays or vermiculite can be presentwithout suffering from the rheological disadvantages presented by thepure minerals.

Drying of Nits

After disperging, the nits generally require input of further energy todry them, as shown in FIG. 1. In some embodiments, the nits, once dried,are substantially free of clumps of multiple nits. Thus, some form ofagitation during drying can be useful. Agitation after drying to breakapart clumps can also be practiced. Once the nits are extruded orremoved from the disperger in their moist state, they can be agitatedand maintained in a loose state during drying or until they aresufficiently dry that hydrogen bonds between nits are unlikely to form.A high-shear air dryer or fluidized bed dryer can be used, wherein jetsof heated air rising from beneath the nits in a tank, drum, rotarydryer, or bed stir and agitate the nits and help maintain them in aloosened state. In one embodiment, jets of air adjacent the exit port ofthe disperger immediately break up the nits and cause both agitation anddrying to begin. Likewise, nits may be dumped, conveyed, orpneumatically blown into rotating drums or tumblers which permit passageof heated gases into the nits. Rotating dryer units, especially thosewith stirring means or spoiler bars are also useful, for the mechanicalstirring or motion of the dryer helps prevent clumping of the nits asthey dry and helps in drying the nits uniformly. Periodic bursts of highvelocity air jets in the dryers to further agitate the particles can behelpful. Any number of commercial particle dryers, fluidized bedssystems, and high shear dryers can be adapted to the purpose of dryingnits, using principles well known to those skilled in the art. Examplesinclude particle processing equipment of Carman Industries, Inc.,including Carman® Fluid Bed Processors such as the Model FBP-1322,Adjust-A-Flow™ Vibrating Feeders, and Vibrating Bin Dischargers (see theWeb pages for Carman Industries).

Useful examples of fluidized bed dryers are the fluid bed dryers ofSwenson Process Equipment (15700 Lathrop Avenue Harvey, Ill. 60426), orthe Swenson rotary dryers and flash dryers.

Other examples of useful dryer means include the “plow dryer” ofProcessall, Inc., (Cincinnati, Ohio), which uses primarily mechanicalmeans to fluidize the particles without high shear or particledegradation. Fluidization is achieved by means of a shaft with attachedmixing elements. This device comprises a vessel with a shaft having aseries of rotating elements (plows), designed to lift and separate theproduct inside the vessel. The design of the blades, the number andspacing of the elements, and the speed all contribute to fluidization.The application of upward moving jets of air in the plow mixer isbelieved to offer advantages over mechanical action alone. Thus, thenits can be dried by a combination of low-shear gaseous fluidization andthe action of rotating plow elements in a tank. In this manner,agglomerates can be broken up and rapid drying can be achieved. However,mechanical shear can replace much of the shear normally provided by gasstreams, as exemplified by the Processall U-MAX Rotary Vacuum Dryers(Cincinnati, Ohio).

Following application of suitable mechanical energy into an elevatedconsistency slurry of fibers, the fibers will generally have becomeentangled into small, dense bundles (nits). The nits can have a meanparticle size of about 50 micrometers to about 1000 micrometers, andmore specifically within the range of from about 100 micrometers toabout 850 micrometers, more specifically still from about 300micrometers to about 850 micrometers, and most specifically from about300 micrometers to about 600 micrometers, as determined by sieveanalysis according to American Society for Testing and Materials (ASTM)test method D-1921. In one embodiment, less than 15% by weight and morespecifically less than 5% by weight of the nits have a particle sizegreater than 2 mm or a size less than 50 micrometers. More specifically,less than 5% by weight of the nits have a particle size greater than 1mm. Most specifically, less than 1% by weight of the nits have aparticle size greater than 1 mm. Alternatively, at least 90% by weightand or, more specifically, at least 95% by weight of the dry nits or dryfree-flowing particles have a particle size, as determined by sieveanalysis (e.g., ASTM method D-1921), of any one of the following ranges:from 100 micrometers to 850 micrometers, from 100 micrometers to 800micrometers, from 300 micrometers to 850 micrometers, from 300micrometers to 600 micrometers. It is understood that the particlesmeasured by sieve analysis may comprise cohesive agglomerates of smallerparticles.

Methods of manufacturing the nits can further comprise subsequenttreatments after drying such as sorting, sieving, screening, winnowing,and the like to remove the largest nits and/or to remove small fibers orother undesired particles. Sorting of the nits by particle size byscreening, sieving, and the like can be done. Sorting or separating canalso be performed by aerodynamic methods (e.g., entrainment in afluidized bed) to remove particles with the largest effective surfacearea or aerodynamic drag, or to sort particles according to density.Cyclones can be effective in sorting particles entrained in air or otherfluids according to the density of the particles. Several usefulprinciples for classification and size reduction of particles aredescribed in “Size Reduction of Solids: Crushing and GrindingEquipment,” by L. G. Austin and O. Trass, Chapter 12 in Handbook ofPowder Science and Technology, ed. by M. E. Fayed and L. Otten, 2^(nd)ed, Chapman & Hall, New York, 1887, pp. 586-634, with particularemphasis on pp. 610-611. Nits can be classified by other methods such asby screening, exemplified by vibrating or gyratory screeners, such asthose described by N. McCauley in “Vibrating and Gyratory Screeners:Proper Installation Yields Top Performance,” in Powder and BulkEngineering, December 1999, pp. 35-39; sieving, including ultrasonicsieving, such as with a SonoScreen® device by Telsonic Ultrasonics(Bridgeport, N.J.), or gyratory sieves. such as the Vort-Siv® ModelRBF-10 gyratory sieve (MM Industries, Salem, Ohio); air classificationsuch as with the NSP Powderizer® by Sturtevant, Inc. (Hanover, Mass.) orMarsulex® Air Classifiers (Marsulex Environmental Technologies, Lebanon,Pa.), or centrifugal air classifiers by CCE Technologies (Eagan, Minn.)and the like. In one embodiment, classification into two or moreparticle sizes is performed with a Coanda-effect gas stream particleclassifier as described in U.S. Pat. No. 6,015,648, “Gas StreamClassifier and Process for Producing Toner,” issued to S. Mitsumura etal., Jan. 18, 2000, herein incorporated by reference.

The dry nits typically have a density above the critical density of thefibers, so that upon being wetted, the individual nits are unlikely tolose substantial volume but can even swell, resulting in increased voidvolume or improved body fit of a pouch of nits in an absorbent article.Nits combined with hydrogel forming materials (superabsorbent particles)are especially likely to swell substantially upon wetting and canimprove body fit through that mechanism.

Other Free-flowing Particles

In addition to cellulosic nits, useful materials for formingfree-flowing particles include polymethyl urea spheres, as disclosed inWO 98/43684, “Absorbent Item,” M. Raidel, Oct. 8, 1998. Microporousmacrobeads can also be used, such as those disclosed by A. J. Disapio etal. in “Microporous Macrobeads Provide New Opportunities in Skin Care,”Soap and Cosmetics, Vol. 75, No. 2, February 1999, pp. 42-47, which arepalpable polymeric beads that may be spherical or formed by attrition ofspheres comprising pores within the bead for retention or release ofchemical agents or liquids. Microporous macrobeads are commonly madefrom acrylate copolymers with added monomers to control surfaceproperties, void volume, etc. For example, ester-rich monomers lead tohighly lipophilic surfaces. Particle size for macrobeads useful in thepresent invention can be from about 100 to 500 microns, or from about300 to 600 microns. Microporous macrobeads may be used alone or incombination with nits, microspheres, beads, or PMU particles. Porous,hollow, or solid spheres of silica and other minerals can also be used,as well as other particle shapes adapted for free flowing performance.Particles that have been coated with anti-stick agents such assilicones, talc, fluorinated polymers, and the like can also providegood flowability in the dry state.

The free-flowing particles can be absorbent but substantiallynon-swelling (i.e., when wetted with 50% moisture by weight, the bulkvolume of the assembled particles increases by less than 20%, or at a200% moisture uptake, the bulk volume of the particles increases by lessthan 25%). When an effective quantity of free-flowing particles aredisposed within a porous pouch or restrained between two webs ofmaterial, with the web closest to the body side of the wearer of theabsorbent article necessarily being porous, the free-flowing particlescan serve both as an effective intake means for the absorption of mensesand other body fluids, and as a body-conforming means for maintaininggood fit against the body and comfort of the wearer. In one embodiment,the free-flowing particles can remain mobile even when wet, particularlywhen previously treated with at least one of lubricants, debonders,surfactants, dispersants or hydrophobic material, and can flow inresponse to shear or compressive forces over a wide range of saturationvalues, permitting the nits to conform to the body and provide comfort.

Two or more kinds of free-flowing particles may be combined. The kindsof particles present in an absorbent article can differ in physicalproperties such as particle size, surface smoothness, wettingcharacteristics, presence of debonder or anti-static compounds or otheranti-clumping agents; density, fiber type, fuzziness or degree offibrillation, etc. Other particles or agents may be added for comfort,compressibility, and tactile properties, including small pieces of soft,deformable foam, such as regular or irregular shaped particles of foamrubber or polyurethane foam, having, by way of example only, a particlesize from about 300 micrometers to 2 mm, and specifically from about 400micrometers to about 1 mm. While the foam or other added particles maynot be highly free flowing or perhaps not free flowing at all by itsself, when combined with a sufficient quantity of free-flowing particlesthe combination can display free flow properties nonetheless. In otherembodiments, one or more kinds of nits can be combined with otherparticles such as microspheres, spherical minerals, coated particles,and the like.

Incorporation into Absorbent Articles

Following drying and other processing steps in the preparation of nitsor other free-flowing particles, the particles are incorporated into anabsorbent article for the absorption of body fluids or other liquids. Inone embodiment, nits comprising papermaking fibers can serve as theabsorbent material in elongated absorbent pads for absorbing oil orother spilled liquids. Illustrative absorbent pigs are detailed incopending patent application Ser. No. 09/119602, “An Elongated LiquidAbsorbent Pad and System for Collecting Leaks and Spills,” filed Jul.22, 1998 by J. D. Cotton, J. J. Tanner, and J. D. Lindsay, hereinincorporated by reference in its entirety. In particular, free-flowingparticles such as eucalyptus nits or sulfite softwood nits encased in anelongated liquid pervious web such as a spunbond web can form theinterior absorbent material of an elongated absorbent pig suitable forcontainment of oil spills and other leaks in an industrial or workplacesetting. The free-flowing particles allow the pig to conform to thesurroundings, which are often irregular, in order to maximize leakprevention and absorption of fluids.

The free-flowing particles of the present invention can also be of valuein many absorbent articles, particularly those adapted to conform to thebody of a wearer, exploiting the ability of free-flowing particles todeform and flow in response to the presence of a body while stillmaintaining high void volume. even when wet. Thus, the free-flowingparticles of the present invention could be used as an absorbentcomponent in sanitary napkins (feminine care pads and related catamenialdevices, including “ultra-thin” pads and pantiliners and maxipads),incontinence pads, diapers, menstrual pants disposable briefs forchildren (training pants), breast pads, bed pads, sweat absorbing pads,helmet liners, body-contacting absorbents for ostomy bags, wounddressings, and the like.

FIG. 2 depicts the cross-section along the transverse centerline of anabsorbent article 20 which, in this embodiment, is a sanitary napkinhaving a longitudinal direction normal to the cross-section shown. Thearticle 20 comprises an absorbent core 22 disposed between a topsheet 24and a liquid impervious backsheet 26, the backsheet 26 being joined tothe topsheet 24 at the periphery 28 of the sanitary napkin 20. Thetopsheet 24 can comprise any fluid pervious cover material known in theart, such as nonwoven webs or apertured films, or other materials suchas hydrophilic wet laid basesheets treated with portions of hydrophobicmatter, including those of Chen et al. in commonly owned copendingapplication, “Dual-zoned Absorbent Webs”, Ser. No. 08/997,287, filedDec. 22, 1997, herein incorporated by reference.

The absorbent core 22 comprises a conformable intake member 30, an upperabsorbent layer 32 and a lower absorbent layer 34. The conformableintake member 30 comprises a longitudinal pouch 36 of free-flowingparticles 38 such as nits. The free-flowing particles 38 can besubstantially free of superabsorbent particles or other powdered orgranular materials, or can be combined with superabsorbent particles orother granular materials if desired.

In the embodiment depicted in FIG. 2, the upper absorbent layer 32 istransversely wider than the lower absorbent layer 34 such that the upperabsorbent layer 32 is held in a convex upwards position, whereininwardly lateral compression of the sanitary napkin 20 from thelongitudinal sides by the legs of the wearer will tend to flex the upperabsorbent layer 32 upward toward the body of the wearer, thus helpingthe conformable intake member 30 to be held in place against the bodyfor good body fit and effective functioning as an intake member.

The upper absorbent layer 32 and the lower absorbent layer 34, as wellas any other absorbent components apart from the free-flowing particles38, can independently be any porous absorbent material known to beuseful in sanitary napkins or other absorbent articles, such as one ormore plies of wetlaid or airlaid tissue; cellulosic airlaid webs ofcomminuted fibers (commonly termed “airfelt”); other dry laid andairlaid webs; coform; creped cellulose wadding; peat moss; absorbentfoams such as the hydrophilic polyether polyurethane foams of U.S. Pat.No. 5,914,125 and foams produced from high internal phase emulsions(HIPE) or other means, including those disclosed in U.S. Pat. No.5,692,939, issued Dec. 2, 1997 to DesMarais, U.S. Pat. No. 5,851,648,issued to K. J. Stone et al., Dec. 22, 1998, or in U.S. Pat. No.5,795,921, issued Aug. 18, 1998 to Dyer et al.; the foam-structuredfibrous absorbent materials of F. -J. Chen et al. disclosed in thecommonly owned, copending U.S. patent application “Fibrous AbsorbentMaterial and Methods of Making the Same,” Ser. No. 09/083,873, filed May22, 1998, herein incorporated by reference; absorbent sponges; syntheticstaple fibers; polymeric fibers; hydrogel-forming polymer gellingagents, fiber-foam composites; absorbent nonwoven webs; cotton; wool;keratin fibers; or any equivalent materials or combinations ofmaterials. The upper absorbent layer 32 and lower absorbent layer 34 canalso comprise superabsorbent particles, fibers coated with or attachedto superabsorbent particles, or other superabsorbent materials.

The nits can comprise papermaking fibers having at least 30% hardwoodfibers and specifically at least about 30% eucalyptus fibers by weight,more specifically at least 60% hardwood fibers by weight. The nits canhave an angle of repose of less than 72° and specifically less thanabout 60° in the dry state and in one embodiment, can still have anglesof repose in the aforementioned ranges even at a moisture content of50%.

The conformable intake member 30 can be elongated in the longitudinaldirection of the article 20, and can have an aspect ratio of 2 orgreater, more specifically about 3 or greater, more specifically stillabout 4 or greater, and most specifically from about 4 to about 8. Thewidth of the conformable intake member 30 can be about 2 cm or greater,or less about 5 cm or less or more specifically about 4 cm or less,while having a length of about 8 cm or greater, more specifically about10 cm or greater, and most specifically about 15 cm or greater. The samedimensional considerations can be applied specifically to the pouch 36itself, as well.

Apart from the added thickness contributed by the pouch of particles 38,the thickness of the absorbent article 20 can be from about 2 mm toabout 50 mm, more specifically from about 3 mm to about 25 mm, morespecifically still from about 3 mm to about 15 mm, and most specificallyfrom about 4 mm to about 10 mm. Ultrathin articles can have a thicknessless than about 6 mm.

Various types of free-flowing particles 38 can be incorporated into oneor more discrete pouches 36 in the article or can be mixed togetheruniformly or in gradient form. Principles and equipment for mixingfree-flowing particles are described by B. H. Kaye in “Mixing ofPowders,” Chapter 11 in Handbook of Powder Science and Technology, ed.by M. E. Fayed and L. Otten, 2^(nd) ed, Chapman & Hall, New York, 1887,pp. 568-585.

The pouch 36 can be a nonwoven web or tissue web adapted to fullyenclose the free-flowing particles 38. However, it need not be a singlematerial forming a complete encasement or envelope for the particles 38,but can be formed by the interaction of a plurality of webs or absorbentlayers to define a sealed volume capable of enclosing free-flowingparticles 38. For example, a pouch 36 can be formed by the interactionof a backsheet 26, an outer absorbent member 42 comprising a centralvoid 44 for receiving free-flowing particles, and a topsheet 24, wherebyattachment of the various components serves to prevent the free-flowingparticles 38 from escaping the article 20.

In one embodiment, the article 20 comprises a pocket of substantiallyloose absorbent material comprising a first type of free-flowingparticles 38 and a second type of particles (not shown) to obtain abalance between various properties such as ability to flow freely whendry or when wet, absorbency, conformability, ability to resist bunching,etc. A third type of particles (not shown) or even more types ofparticles can also be present. In one embodiment, the first type ofparticles 38 is hardwood nits, optionally comprising 50% or more of themass of the absorbent material in the pocket. The second type ofparticles can be other cellulosic nits, such as, for example, softwoodnits having a substantially larger particle size than the first type ofparticles. The second type of particles, like the first type, can betreated with a small quantity (e.g., less than 5% by dry mass, or lessthan 1% by dry mass) silicones or other hydrophobic materials optionallyresiding primarily on the surface of the particles to help preventsticking or clumping of particles when wet. Thus, in one embodiment, thecentral absorbent member 46 comprises loose nits of fibrous materialcomprising a first type of free-flowing particles 38 and a second typeof free-flowing particles, substantially distinguished in a materialproperty selected from fiber type, mean particle size (determined bysieve analysis according to American Society for Testing and Materials(ASTM) test method D-1921), ash content, chemical additive content,Water Retention Value, and wetting angle of the surface of theparticles. Superabsorbent particles and odor control materials can bepresent as the second type or third type of particles or as a portion ofa mix or composite comprising the second or third type of particles.When superabsorbents or hydrogel-forming materials are incorporated withnits, they can be present in an amount greater than 0 to less than 100weight percent, specifically from about 5 to about 95 weight percent,more specifically from about 15 to about 85 weight percent, and morespecifically still from about 20 to about 50 weight percent, based onthe total weight of the superabsorbent or hydrogel-forming polymericmaterial and nits in the absorbent composition. In one embodiment, lessthan about 10% superabsorbent particles are present for nits treatedwith hydrophobic material, in order to help maintain a free flowingnature of the nits even when wetted.

In one embodiment, nits or other free-flowing particles 38 such ashollow spheres are combined with deformable particles having, by way ofexample only, a particle size of about 2 mm or less, more specificallyabout 0.7 mm or less, including pieces of a soft foam such as apolyurethane foam or foam rubber material. Rounded particles can beused. The soft, deformable particles combined with the can help improvethe tactile properties of the filled pouch 36, allowing a softer feeland more comfort when worn against the body. In general, the freeflowing particles 38 for use in any of the absorbent members of thepresent invention can be combined with one or more deformable materials,particularly in particulate form, for improved comfort and avoidance ofa grainy feel, especially when larger sized free-flowing particles areused.

The topsheet 24 can be any material known to be useful as topsheets inabsorbent articles. Exemplary topsheets can be made in accordance withU.S. Pat. No. 5,533,991, issued Jul. 9, 1996 to Kirby et al.; U.S. Pat.No. 4,342,314 issued Aug. 3, 1982 to Radel et al. and U.S. Pat. No.4,463,045 issued Jul. 31, 1984 to Ahr et al. The topsheet 24 maycomprise an additional transfer layer (not shown) to help direct fluidinto the absorbent core 22, as disclosed, for example, in U.S. Pat. No.4,397,644, issued Aug. 9, 1983 to Matthews et al. The topsheet 24 maycomprise one or more layers of microdenier fibers, such as thosedisclosed in European Patent Application 893,517-A2, “Micro-DenierNonwoven Materials Made Using Modular Die Units,” A. Fabbricante, etal., published Jan. 27, 1999. The topsheet 24 need not have uniformproperties but can be preferentially more permeable or liquid perviousor wettable over the central absorbent member than it is elsewhere.

The backsheet 26 may be any flexible, liquid impervious material thatprevents discharges collected by the absorbent article 20, such as asanitary napkin, from escaping the article 20 and soiling theundergarments and clothing of the wearer.

The backsheet 26 and other components may be biodegradable and/orflushable. A flushable article is one that can be directly discardedinto a toilet and flushed without clogging piping and without harm toseptic systems. The backsheet 26 may also be extensible or elasticallydeformable for use in extensible absorbent articles. Any methods knownin the art for production of elastic or stretchable films or coversheets may be used, including those disclosed in U.S. Pat. No.5,702,378, issued to Widlund et al., Dec. 30, 1997 and in U.S. Pat. No.5,824,004, issued Oct. 20, 1998 to Osborn, III et al.

FIG. 3 depicts an absorbent article 20 related to that of FIG. 2 andgenerally follows the number scheme of FIG. 2. However, the absorbentcore 22 of the absorbent article 20 further comprises an outer absorbentmember 42 with a central void 44 therein for receiving the lowerabsorbent layer 34 and the upper absorbent layer 32, which, togetherwith the conformable intake member 30 form a central absorbent member 46that is laterally surrounded by the outer absorbent member 42. Thecentral absorbent member can comprise from 0.5 grams to about 10 gramsof dry nits, specifically from about 2 grams to 5 grams, and cancomprise from about 0 grams to 5 grams of superabsorbent particles orfibers.

A wicking barrier 48 separates the outer absorbent member 42 from thecentral absorbent member 46. The wicking barrier 48 is a section ofpolymeric film or other flexible, hydrophobic or liquid imperviousmaterial to help contain fluid within the central absorbent member 46and to reduce lateral flow therefrom to the longitudinal sides of thearticle 20. For example, the wicking barrier 48 can be a polyolefinfilm, a fluid-resistant nonwoven web, a tissue treated to behydrophobic, or the transfer delay barrier materials disclosed in thecommonly owned U.S. patent application Ser. No. 60/079,657, “AnAbsorbent System for Personal Care Products Having Controlled Placementof Visco-Elastic Fluids” by A. S. Burnes et al., herein incorporated byreference.

The wicking barrier 48 is optionally provided with apertures forcontrolled release of fluid from the central absorbent member 46 to theouter absorbent member 42. As depicted, the wicking barrier 48 has anunderlying portion 50 beneath the lower absorbent layer 34, a verticalcomponent 52 spanning a vertical distance between the outer absorbentmember 42 and the central absorbent member 46, and a horizontalcomponent 54 spanning a horizontal distance on or above the body-sidesurface of the outer absorbent member 42. The wicking barrier 48 helpsprevent fluid communication between the outer absorbent member 42 to thecentral absorbent member 46 not only by impairing lateral wicking, butby obstructing contact between the two absorbent members 42, 46 when thearticle 20 is worn and laterally compressed. The Intrinsic AbsorbentCapacity of the barrier material can be about 1 or less, morespecifically less than about 0.5, more specifically still less thanabout 0.3, and most specifically less than about 0.1. The material ofthe wicking barrier 48 can be substantially non-absorbent.

The outer absorbent member 42 can be a contiguous piece of absorbentmaterial with a central hole, or can be two longitudinal strips ofabsorbent material wherein the central void 44 is defined by the spacebetween the two strips.

FIGS. 4A and 4B depict the transverse cross-section of an absorbentarticle 20 also comprising a central absorbent member 46 comprising anupper absorbent layer 32 and a pouch 36 comprising free-flowingparticles 38 in a pouch 36 disposed beneath the upper absorbent layer32; an outer absorbent member 42 having a central void 44 for receivingthe central absorbent member 46; a wicking barrier 48 disposed betweenthe central absorbent member 46 and the outer absorbent member 42. Thepouch 36 is narrower than the upper absorbent layer 32. The upperabsorbent layer 32 therefore assumes a convex upward shape predisposedto flex toward the body of the wearer during inwardly lateralcompression from the longitudinal sides of the article 20.

The wicking barrier 48 extends below the pouch 36 of free-flowingparticles 38 and has a vertical component 52 spanning a verticaldistance along the inner walls of the central void 44 of the outerabsorbent member 42, and further has a horizontal component 54 spanninga horizontal distance on the body-side surface of the outer absorbentmember 42. The wicking barrier 48 can comprise multiple sections, suchas two strips of polymeric film or two strips of a substantially liquidimpervious nonwoven web extending along the longitudinal sides of theupper absorbent layer 32 to hinder wicking between the central absorbentmember 46 and the outer absorbent member 42.

In FIG. 4A, the outer absorbent member 42 is divided along thetransverse centerline by a central void 44 passing completely throughthe outer absorbent member 42, while in FIG. 4B, the outer absorbentmember 42 is not divided but comprises a relatively thinner underlyingportion 50 beneath the central absorbent member 46 and joining the twolongitudinal sides of the outer aosorbent member 42 along the transversecenterline. In FIG. 4B, the central void 44 is a depression and not ahole passing completely through the outer absorbent member 42. Thus, thepouch 36 can be disposed between two or more layers of absorbentmaterial or particle restraining material (including the wicking barrier48), in which case the free-flowing particles 38 can be restrained bythe surrounding materials without the need for the pouch 36 depicted inthe embodiment of FIG. 4B.

FIG. 5 is a partial cutaway view of an absorbent article 20 according tothe present invention. The article 20 comprises a topsheet 24, which iscut away to reveal several underlying components, particularly an upperabsorbent member 32, which has a medial hump therein due to the presenceof an underlying pouch 36 of free-flowing particles, depicted here in atruncated oval shape having a thickness substantially greater than thethickness of the upper absorbent member 32. The upper absorbent member32 further comprises a pair of optional, substantially longitudinalcrease lines 56′, 56″ in the crotch region 60, the crease lines 56′, 56″being spaced apart about the longitudinal centerline of the article 20.The crease lines 56′, 56″ are transversely outside the longitudinalsides of the pouch 36 and within the longitudinal sides 58′, 58″ of theupper absorbent member 32. The crease lines 56′, 56″ also extend intothe underlying lower absorbent member 34, which also has a thicknesssubstantially lower than the pouch 36 of free-flowing particles in thisembodiment. Thus, the crease lines 56′, 56″ in both the upper absorbentmember 32 and the lower absorbent member 34 permit upward folding of theouter longitudinal sides of the lower absorbent member 34 and the upperabsorbent member 32 to form a valley fold when the absorbent article 20is laterally compressed inward by the legs of the user when worn, whilethe elevated pouch 36 helps contribute to the formation of a centralmound when compressed laterally inward to give an overall W-shape to thearticle 20 (with the central part of the W-shape in one embodiment beingsubstantially rounded).

In one embodiment, the upper absorbent member 32 and the pouch 36 canpartially separated from the lower absorbent member 34 by a horizontalwicking barrier (not shown).

FIG. 6 depicts cross-sectional views along transverse centerlines ofabsorbent articles showing several ways in which a pouch 36 of nits orother free-flowing particles 38 can serve as a conformable intake memberdisposed on an upper absorbent layer 32. In FIG. 6A, the pouch 36 isdisposed in a central void 44 within the upper absorbent layer 32. InFIG. 6B, the pouch 36 is disposed in a central void 44 passingcompletely through the upper absorbent layer 32, with second layer, thelower absorbent layer 34 beneath the pouch 36. The lower absorbent layer34 is preshaped to have a convex upward shape to predispose it to flexupward when inwardly laterally compressed, thus directing the pouch 36toward the body. In FIG. 6C, the upper absorbent layer 32 is preshapedfor upward deflection when inwardly laterally compressed from thelongitudinal sides. The upper absorbent layer 32 has a central shapingline 62 where the lower absorbent layer 34 has been scored, folded,stamped, embossed, or the like to promote upward flexure. A resilientdeflection element 64 comprising a central hinge 66 is further disposedbeneath the upper absorbent layer 32 to further control the deflectionof the absorbent article toward the body of the wearer when the articleis worn.

FIG. 7 shows a partial cutaway view of an absorbent core 22 for use inan absorbent article (not shown) according to the present invention. Theabsorbent core 22 comprises an outer absorbent member 42 having acentral elliptical hole therein for receiving a central absorbent member46. The outer absorbent member 42 can be an outer annular ring ofabsorbent material. The central absorbent member 46 comprises an innerannular ring 68 of absorbent material with an inner void therein, and aconformable intake member 30 comprising nits or free-flowing particles38 in a liquid-pervious pouch 36 which prevents particles from escapingthe conformable intake member 30.

Between the outer absorbent member 42 and the central absorbent member46 is a wicking barrier 48, which comprises a vertical component 52 anda horizontal component 54 on or above the body-side surface of the outerabsorbent member 42.

FIG. 8 shows a “pillow pad” design based on the Raidel patentapplication (WO 98/01684), adapted according to the present invention tocomprise nits. FIG. 7 shows a pad 20 in partial section view. The pad 20comprises a frontal region 70, a middle region 72 and a rear region 74.A liquid-pervious layer topsheet 24 and a liquid-impervious backsheet 26are joined together at the periphery 28. The absorbent core 22 comprisesa central absorbent member 46 and an outer absorbent member 42. Thecentral absorbent member 46 comprises a pouch 36 containing cellulosicnits 38 therein. The pouch 36 may be made from a nonwoven web.

In the embodiment shown in FIG. 8, the pouch 36 is almost entirelyfilled with free-flowing particles 38 such as nits. Complete fillingwith nits does not pose any serious problem in use since the nits do notexpand substantially upon wetting. If substantially swellable materialswere also present, such as superabsorbent particles, the pouch 36 can beonly partially filled with absorbent material to prevent rupture.Alternatively, the pouch 36 can comprise elastomeric material or pleatsor folds that can allow the pouch 36 to expand when the free-flowingparticles 38 and other absorbent materials inside the pouch 36 arewetted.

Grooves 76 extend in the longitudinal direction of the article 20. Thepouch 36 of the absorbent core comprises tied-in areas 78 which cause adegree of separation of the pouch 36 into a central chamber 80 andlateral chambers 82, 84. The delimitation walls of the individualchambers do not reach all the way to the base of the pouch 36, so that alimited degree of material exchange can occur between the individualchambers.

As shown in FIG. 8, the pouch 36 comprises two sections which areinterconnected at the peripheral margins 86 of the pouch 36. Thisconstruction facilitates filling of the absorbent core 22 withfree-flowing particles 38 because a lower half of the pouch 36 can befilled with particles, and then an upper half can be placed over thelower half of the pouch 36 to seal the free-flowing particles 38.

The pouch 36 depicted in FIG. 8 is substantially oval in shape and isbacked by additional absorbent material in a lower absorbent layer 34 ofthe central absorbent member 46. The lower absorbent layer 34contributes to wearer comfort and to absorbency of the absorbent core22.

A wicking barrier (not shown) may also be present between the centralabsorbent member 46 and the outer absorbent member 42. The lower surfaceof the lower absorbent layer 34 may comprise a polymeric film which canextend past the peripheral margins 86 of the central absorbent member 46such that some of the wicking barrier also extends on the body-sidesurface of the outer absorbent member 42 in the middle region 72 (crotchregion) of the absorbent article 20 for improved leakage control.

Without wishing to be bound by theory, it is believed that when thearticle 20 comes into contact with menses or blood, the grooves 76 helpdistribute the fluid longitudinally, after which fluid can be taken upby the free-flowing particles 38 in the pouch 36. The grooves 76 arealso believed to provide increased transverse flexibility of theabsorbent article 20, providing for good body fit and comfort, whilereducing the effective size of any one chamber 80, 82, 84, such thatshifting of the particles 38 is not a serious problem.

FIGS. 9 and 10 were previously discussed in relation to the Angle ofRepose test.

FIGS. 11 and 12 were previously discussed in relation to the Gel BedPermeability test.

FIG. 13 depicts a flowchart for a process of making nits in which thestream of fibers is disperged more than once, allowing modifications inchemistry and process conditions to permit improved control over nitproperties in the two or more separate steps. It has been discoveredthat a second step of disperging can help improve the flowability andabsorbency properties of the nits. Thus, hardwood fibers or a slurrycomprising hardwood fibers can be substantially curled or formed intonits in a first disperging operation, such as by treatment with a Mauledisperger, a BIVIS disperger, a disk disperger, or other suitableequipment capable of curling and disperging high-consistency wood pulp.The mechanically treated fibers or nits can then be optionally dried,followed by adjustment of the moisture content to bring the consistencyto about 18% or greater, or 20% or greater, such as from 20% to 30%.Thereafter the fibers are again subjected to disperging at a suitableenergy level to create nits, which are then dried. For example, a Mauleshaft disperger can be used to create nits in a first step with an exitconsistency of about 30% or higher, whereafter the consistency isreduced to from about 20% to about 30% for further mechanical processingin a Hobart mixer for high-consistency pulp. Without wishing to belimited by theory, it is believed that a second disperging step underdifferent processing conditions (different consistency or differentmechanical equipment) can create new shear conditions that may helpremove free fibers projecting from the surface of nits formed in thefirst step, fibers that may not have been sufficiently able to becomeentangled into the nit under the conditions of the first treatment.

The use of two or more disperging steps provides increased flexibilityto achieve specific objectives. For example, nit conditioners anddisperger conditions in the first disperging step may be designed tocontrol flock formation and the initial size of the nits to maximizeyield in a desired size range. The second disperging step may furtherimproved the size distribution and may use different chemistry aimed atmodifying the surface of the nits rather than the body of the nits. Inthis way improved control over nit properties is possible.

In addition, without wishing to be bound by theory, it is believed thatdrying or partial drying after a first disperging step, followed byremoistening, a second disperging step, and final drying, can promotehydrogen bonding of previously loose fibers with the parent nits suchthat the fibers are no longer projecting from the nits to the degreebefore. By remoistening partially dried nits and drying the nits again,new hydrogen bonds can form between loose fibers and the other fibers inthe nits from which the loose fibers project. If the nits are simplywetted and redried, new hydrogen bonds may form between projectingfibers and other nits, resulting in clumps. Disperging or mechanicalshear is needed after rewetting to separate the nits and promote bondsbetween fibers in the same nit rather than bonds between nits. Followingthe second disperging step, entanglements between adjacent nits willhave been largely disrupted by the mechanical action and tighter, densernits will have been formed. Drying can then be completed, optionallywith pneumatic or mechanical agitation to prevent additional clumping.

Further, the use of two or more disperging steps offers additionalcombinations of temperature and chemistry to control the properties ofthe nits. For example, the first disperging step may be done at anelevated pH (e.g., pH above 8, such as from 9 to 11), wherein the fibersare swollen and relatively flexible. Then the second disperging step maybe performed under lower pH, such as a pH of from about 4 to 6, whereinthe swelling of the fibers are reduced and the ability of the fibers tocollapse into nits may be enhanced. Benefits can also be obtained by thereverse procedure, in which a first disperging step is conducted at lowpH, followed by a second step at elevated pH, with the potential toproduce nits that are relatively more round or that have other desiredmorphological properties.

By disperging nits in two or more stages, a first chemical can be addedin a first disperging step, followed by addition of a second chemical ina second disperging step. This can be particularly helpful when the twochemicals would give undesired reactions when added simultaneously, suchas an anionic compound and a cationic compound. For example, an anionicanti-microbial compound and a cationic wet strength agent or cationicdebonder could be added in separate disperging steps. Or two chargedcompounds can be added that would normally interfere with each other orcause precipitation.

FIG. 14 depicts a flowchart for preparing an absorbent articlecomprising two or more kinds of nits. Nits of a first fiber type and asecond fiber type are prepared via disperging in the presence of nitconditioners and then dried, forming two material streams that can beindependently exposed to post-treatments such as sorting by size bysieving, screening, or other classification methods, and such aschemical treatment, including deposition of hydrophobic matter on aportion of the outer surface of the nits. The nits can then be combinedand used to fill a pouch in an absorbent article. Alternatively, thenits may be combined prior to any of the post-treatments or even priorto drying. When sorting by size or other properties occurs as apost-treatment, a fraction of the particle will be rejects that can berecycled (e.g., repulped and used in nits production, or used in otherprocesses) or discarded. This can be generally true for all nitsproduction methods of the present invention, even when not explicitlystated. The accepts are used to prepare the absorbent article.

FIGS. 15 to 17 show SEM micrographs of eucalyptus nits preparedaccording to conditions identified below in the Examples. FIG. 15 showsa rounded, ovoid nit substantially free of fibers ascending from the nitthat could readily become entangled with other nits. The nit shown inFIG. 16 is still relatively free of fibers ascending from the surface,though it appears that two fibers do ascend. FIG. 17 is a cross-sectionof another eucalyptus nit produced with a Maule disperser, which was cutby a blade after being frozen in liquid nitrogen to reveal the interiorstructure.

Other Additives and Treatments

In one embodiment, known cationic retention aids are added to the pulpfibers prior to nit formation to promote and control floc formulation.Retention aids known in papermaking include a variety of cationicpolymers such as polyacrylamides, cationic starch, modified guar gum, ordual-component retention aid systems, such as COMPOZIL® cationicpolymer-colloidal silica microparticle systems, can be useful incontrolling the size of nits formed from a papermaking slurry of woodfibers. Related principles are discussed by S. Main and P. Simonson in“Retention Aids for High-speed Paper Machines,” Tappi Journal, Vol. 82,No. 4, pp. 78-84, herein incorporated by reference. For example, addinga cationic starch or polymer such as polyacrylamide to a pulp slurryfollowed by subsequent addition of anionic silica or other anioniccompounds, according to Main and Simonson, can be effective in promotingformation of small, dense, flocs, which, in one embodiment, can be auseful treatment preparatory to forming the nits of the presentinvention. Compounds comprising certain metal ions, such as alum orferric chloride, can also be useful in promoting and controlling flocformation.

The additives may be provided in the furnish prior to mechanicalprocessing, or injected during the disperging process or othermechanical treatments prior to drying, or applied to the exteriorsurface of the nits before, after, or during drying. For additivesintended to improve lubricity and prevent clumping of the particles, theadditives can be preferentially distributed on the surface of theparticles, so the additive in pure form or as a solution can be appliedto the exterior of the particles after their formation and optionallyduring or after the drying process. Additives may be applied by spray,by contact with a wetted surface, by trickling of a stream into a mixedbed of particles, and the like. The additives may be applied uniformlyor nonuniformly to the surface of treated particles, and all or suitableonly a portion of the particles may be treated. In one embodiment, from5% to 90% of the particles are treated, specifically from about 10% to70%, more specifically from 10% to 50%, and most specifically from about10% to about 30% of the particles are treated.

In one embodiment, nits are disperged with added ammonium zirconiumcarbonate, such as 0.3 to 3 weight percent based on dry fiber mass,followed by treatment at elevated temperature (greater than 100° C.),optionally in a fluidized bed or high shear air drier, to crosslink thefibers inside the nits but not between the nits, maintaining a loosebulk structure in the dried product. Ammonium zirconium carbonate canact as a crosslinker and can impart lubricity, promoting a free-flowbehavior in the nits and optionally contributing to useful tactileproperties. Minerals and fillers such as clays and zeolites may also beadded to the fibers in making nits, for odor control, absorbencycontrol, anti-microbial control, or other purposes.

In another embodiment, the nits are treated with both a debonder andcrosslinking agent. Specifically, it is within the scope of theinvention to add both a debonding agent a latent crosslinking agent tothe pulp prior to completion of drying of the nits. Without wishing tobe bound by theory, a beneficial interaction between debonders andcrosslinkers in some embodiments may be expected due the ability ofdebonders to promote formation of nits in a useful size range whilecrosslinkers can further enhance the ability of nits to maintain theirshape and size when wetted, or can be used to attach or retain desiredadditives in the nits. Useful principles for treatment of pulp or fiberswith debonders and crosslinkers are described in U.S. Pat. No.5,225,047, “Crosslinked Cellulose Products and Method for TheirPreparation,” issued to Graef et al., Jul. 6, 1993, herein incorporatedby reference. Likewise, a beneficial interaction between surfactants andcrosslinkers is expected, according to the present invention.

In one embodiment, the debonding agent or surfactant is added to thepulp prior to the addition of the latent crosslinking agent. The latentcrosslinking agent can be added to cellulose while it is at a moisturecontent greater than about 10%, more specifically greater than about30%. Crosslinking is substantially completed during subsequent drying orafter drying in an additional curing step at elevated temperature.

The latent crosslinking agent may be selected from any of the followingwell known materials which serve this function. Types are selected fromurea derivatives such as methylolated urea, methylolated cyclic ureas,methylolated lower alkyl substituted cyclic ureas, dihydroxy cyclicureas, lower alkyl substituted dihydroxy cyclic ureas, methylolateddihydroxy cyclic ureas, and mixtures of any of these types. One latentcrosslinking material is dimethyloldihydroxyethyleneurea (DMDHEU,1,3-dihydroxymethyl-4,5-dihydroxy-2-imidazolidinone). This material isreadily commercially available in a stable form. Other urea-basedmaterials which are eminently suitable include dimethylol urea (DMU,Bis[N-hydroxymethyl]urea), dihydroxethyleneurea (DHEU,4,5-dihydroxy-2-imidazolidinone), dimethylolethylene area (DMEU,1,3-dihydroxymethyl-2-imidazolidinone), and4,5-dihydroxy-1,3-dimethyl-2-imidazolidinone (DDI,dimethyldihydroxyethyleneurea).

In addition to those latent crosslinking agents based on urea, othermaterials that are suitable are polycarboxylic organic acids. Amongthese is 1,2,3,4-butanetetracarboxylic acid.

All of the crosslinking agents just described may be reacted with thecellulose either during normal drying of the sheeted material orsubsequent to this time by raising the pulp or nits to an elevatedtemperature, typically above 100° C.

A neutral or acidic catalyst may be included with the latentcrosslinking agent to increase the reaction rate between the crosslinkerand the cellulose. Acidic salts are particularly useful as catalystswhen the urea-based materials are employed. These salts may typically beammonium chloride or sulfate, aluminum chloride, magnesium chloride ormixtures of these or many other similar materials. Alkali metal salts ofphosphorous-containing acids, such as sodium hexametaphosphate andsodium hypophosphite, with or without additional oxalic acid, are usefulcatalysts for 1,2,3,4-butane carboxylic acid.

The crosslinking agent is typically present in an amount in the range ofabout 0.1% to about 15% (weight percent based on the mass of dry fiber),specifically from about 0.3% to about 6%, and more specifically fromabout 0.5% to about 3%. Similarly, the debonding agent is generallypresent in an amount of about 0.1% to about 10% (weight percent based onthe mass of dry fiber), specifically from about 0.3% to about 4%, andmore specifically from about 0.5% to about 2%. Generally, there will beno need for washing of the pulp after the crosslinking reaction iscompleted.

In one embodiment, the conversion of fibers into dense, free flowingnits can be achieved using two or more steps of disperging or kneading.In some experimental work, it has been discovered that a second step ofdisperging or high-consistency mechanical shearing can help improveflowability and absorbency properties of the nits. Thus, hardwood fibersor a slurry comprising hardwood fibers can be substantially curled orformed into nits in a first disperging or kneading operation, such as bytreatment with a Maule disperger, a BIVIS disperger, a disk disperger,or other suitable equipment capable of curling and disperginghigh-consistency wood pulp. The mechanically treated fibers or nits canthen be optionally dried, followed by adjustment of the moisture contentto bring the consistency to about 20% or greater, such as from 20% to30%. Thereafter the fibers are again subjected to mechanical kneading ordisperging at a suitable energy level to create nits, which are thendried. For example, a Maule shaft disperger can be used to create nitsin a first step with an exit consistency of about 30% or higher,whereafter the consistency is reduced to from about 20% to about 30% forfurther mechanical processing in a Hobart mixer for high-consistencymixing and kneading. Without wishing to be limited by theory, it isbelieved that a second dispersing step under different processingconditions (different consistency or different mechanical equipment) cancreate new shear conditions that may help remove free fibers projectingfrom the surface of nits formed in the first step, fibers that may nothave been sufficiently able to become entangled into the nit under theconditions of the first treatment.

In addition, it is believed that drying or partial drying after a firstdisperging step, followed by remoistening, a second disperging step, andfinal drying, can promote hydrogen bonding of previously loose fiberswith the parent nits such that the fibers are no longer projecting fromthe nits to the degree before. In other words, it is believed that theparticularly good nit properties achieved in two disperging steps withintermediate drying can be explained in terms of hydrogen bonding. Byremoistening partially dried nits and drying the nits again, newhydrogen bonds can form between loose fibers and the other fibers in thenits from which the loose fibers project. If the nits are simply wettedand redried, new hydrogen bonds may form between projecting fibers andother nits, resulting in clumps. Disperging or mechanical shear isneeded after rewetting to separate the nits and promote bonds betweenfibers in the same nit rather than bonds between nits. Following thesecond disperging step, entanglements between adjacent nits will havebeen largely disrupted by the mechanical action and tighter, denser nitswill have been formed. Drying can then be completed, optionally withagitation to prevent additional clumping. But if the consistency of thenits is sufficiently high after the second disperging step, such as atleast about 30% and specifically at least about 40%, relatively littleagitation may be needed during drying because the nits will have littletendency to clump, especially if debonder is present.

Further, the use of two or more disperging steps offers the opportunityfor unique combinations of temperature and chemistry better tailor theproperties of the nits. For example, the first disperging step may bedone at an elevated pH (e.g., pH above 8, such as from 9 to 11), whereinthe fibers are swollen and relatively flexible. Then the seconddisperging step may be performed under lower pH, such as a pH of fromabout 4 to 6, wherein the swelling of the fibers are reduced and theability of the fibers to collapse into nits may be enhanced. Benefitscan also be obtained by the reverse procedure, in which a first kneadingor disperging step is conducted at low pH, followed by a second step atelevated pH, with the potential to produce nits that are relatively moreround or that have other useful morphological properties.

Another benefit of disperging nits in two or more stages is that a firstchemical can be added in a first disperging step, followed by additionof a second chemical in a second disperging step. This can beparticularly helpful when the two chemicals would give undesiredreactions when added simultaneously, such as an anionic compound and acationic compound. For example, an anionic anti-microbial compound and acationic wet strength agent or cationic debonder could be added inseparate disperging steps. Or two charged compounds can be added thatwould normally interfere with each other or cause precipitation.

Nit Properties and Incorporation into Absorbent Articles

Two or more types of nit materials may be combined in a single absorbentproduct, generally by incorporation of the nits into the centralabsorbent section and particularly as a component of the upper absorbentmember, though nits or other free flowing absorbent material can also beused in the central absorbent member if the material is sufficientlyrestrained or under sufficient tension that the shape directing role ofthe central absorbent member is not compromised. The nits or other freeflowing absorbent particles may be blended or layered within an enclosedpouch or pocket or may be distributed in two or more enclosed pouches orpockets, especially pockets having a longitudinal orientation and alength substantially greater than their width. The pocket or pouch isgenerally formed by joining two particle restraining layers togethersuch that a region between the two layers is open and able to receiveparticles. Particle restraining layers can include a topsheet, abacksheet, a layer of absorbent material such as an airlaid web ortissue layer, a polymeric film or nonwoven web in general, and the like,such that the nits are not able to escape from the article under normalconditions of use. The same applies to other loose particles or chips ofmaterial as well, including superabsorbent particles and fibers;mixtures of nits and absorbent polymers; encapsulated materials; starchglobules; loose curled fibers and/or loose crosslinked fibers, such asthose of U.S. Pat. No. 5,190,563, issued Mar. 2, 1993 to Herron et al.,herein incorporated by reference; chips of densified BCTMP; other chipsor particles of densified cellulosic materials, and particularlyabsorbent materials that remain free flowing when wet, such as thematerials disclosed in WO 98/43684, “Absorbent Item,” M. Raidel, Oct. 8,1998; and the like. Raidel in particular discloses the use offree-flowing materials such as hollow spheres of polymethylurea with anabsorbent capacity of greater than about 10 grams of fluid per gram offree-flowing absorbent. Another class of potentially useful free-flowingparticles is microporous macrobeads, such as those disclosed by A. J.Disapio et al. in “Microporous Macrobeads Provide New Opportunities inSkin Care,” Soap and Cosmetics, Vol. 75, No. 2, February 1999, pp.42-47, which are palpable polymeric beads that may be spherical orformed by attrition of spheres comprising pores within the bead forretention or release of chemical agents or liquids. Microporousmacrobeads are commonly made from acrylate copolymers with addedmonomers to control surface properties, void volume, etc. For example,ester-rich monomers lead to highly lipophilic surfaces. Particle sizecan be from about 100 to 500 microns, or from 50 to 100 microns, orabout 50 microns or less. Microporous macrobeads may be used alone or incombination with nits, microspheres, beads, or PMU particles.

Various types of nits or other free-flowing particles can beincorporated in discrete pouches or layers in an absorbent article, orcan be mixed together uniformly or in gradient form. Principles andequipment for mixing free-flowing particles are described by B. H. Kayein “Mixing of Powders,” Chapter 11 in Handbook of Powder Science andTechnology, ed. by M. E. Fayed and L. Otten, 2^(nd) ed, Chapman & Hall,New York, 1887, pp. 568-585.

Nits and other free-flowing particles can be placed in a centraldepression in an outer absorbent member, restrained beneath by absorbentmaterial or by an underlying backsheet, and then the nits can berestrained from above by a superposed topsheet that is adhesivelyattached to the surrounding portions of the outer absorbent member.Multiple layers of nits or other free flowing particles can be added. Aporous web serving as a top restraint for a first layer of nits canserve as the lower restraint for a second layer, which in turn can berestrained from above by a topsheet or other porous web with pore sizesufficiently small to restrain the nits or particles. In one embodiment,the nits are tightly packed into the pocket or pouch such that somepositive tension is maintained on the encasing sections of the pocket orpouch even when the article in unrestrained, for particles that are tooloose and free to shift can fail to conform well to the body in used.

In one embodiment, the absorbent core and optionally the centralabsorbent member has a pocket of substantially loose absorbent materialcomprising a first type of particles and a second type of particles toobtain a balance between various properties such as ability to flowfreely when dry or when wet, absorbency, conformability, ability toresist bunching, etc. A third type of particles or even more types ofparticles can also be present. In one embodiment, the first type ofparticles is hardwood nits, comprising by way of example only 50% ormore of the mass of the absorbent material in the pocket. The secondtype of particles can be other cellulosic nits, such as, for example,softwood nits having a substantially larger particle size than the firsttype of particles. The second type of particles, like the first type,can be treated with a small quantity (e.g., less than 5% by dry mass,and specifically less than 1% by dry mass) silicones or otherhydrophobic materials which can residing primarily on the surface of theparticles to help prevent sticking or clumping of particles when wet.Alternatively, the second type of particles can be a mixture ofcellulose and minerals such as kaolin or bentonite (resulting in a highash content relative to mineral free cellulosic fibers), or may becrosslinked fibers or crosslinked nits (in which case the waterretention value of the crosslinked nits will generally be substantiallylower than for nits that are not crosslinked), or may befiber-superabsorbent composites such as fibers wrapped around hydrogelmaterial. A useful crosslinking agent is ammonium zirconium carbonate,which can be applied to a fiber slurry before making nits at a dosage,for example, from about 0.3 to 3% by weight, and then subjecting thenits to elevated temperature to effect crosslinking. The lubricityprovided by the ammonium zirconium carbonate can be beneficial for theuse of nits in the absorbent article. Wet strength agents such as Kymenecan also be beneficial in controlling wet properties of the nits andincreasing their ability to maintain bulk or remain free flowing whenwet. Thus, in one embodiment, the central absorbent member comprisesloose nits of fibrous material comprising a first type of nits and asecond type of nits, substantially distinguished in a material propertyselected from fiber type, mean particle size (determined by sieveanalysis according to American Society for Testing and Materials (ASTM)test method D-1921), ash content, chemical additive content. WaterRetention Value, and wetting angle of the surface of the nits.Superabsorbent particles and odor control materials can be present asthe second type or third type of particles or as a portion of a mix orcomposite comprising the second or third type of particles. Whensuperabsorbents or hydrogel-forming materials are incorporated with thenits, they can be present in an amount greater than 0 to less than 100weight percent, specifically from about 5 to about 95 weight percent,more specifically from about 15 to about 85 weight percent, and morespecifically still from about 20 to about 50 weight percent, based onthe total weight of the superabsorbent or hydrogel-forming polymericmaterial and nits in the absorbent composition. In one embodiment, lessthan about 10% superabsorbent particles are present for nits treatedwith hydrophobic material, in order to help maintain a free flowingnature of the nits even when wetted.

In one embodiment, nits or other free-flowing materials such as hollowspheres are combined with deformable particles that can have a particlesize of about 2 mm or less, more specifically about 0.7 mm or less,including pieces of a soft foam such as a polyurethane foam or foamrubber material. Rounded particles are produced in some embodiments. Thesoft, deformable particles combined with the nits help improve thetactile properties of the pouch of nits, allowing a softer feel and morecomfort when worn against the body. In general, the nits or other freeflowing particles for use in any of the absorbent members of the presentinvention can be combined with one or more deformable materials,particularly in particulate form, for improved comfort and avoidance ofa grainy feel, especially when larger sized free-flowing particles areused.

The nits can be enclosed in an encasement which is a thin, flexible,liquid pervious fibrous layer such as a spunbond web that encircles thenits and restrains them such that they do not escape the article orshift to undesired portions of the article. The encasement forms apocket or pouch for holding the nits. In one embodiment, the pocket orpouch holding the nits can be substantially centered about thelongitudinal axis of the article and can be located in the crotch regionthereof.

In one embodiment, the nits in an absorbent article are disposed towardthe body side surface and have at least one absorbent web between thenits and the backsheet. The nits can be contained within a frameworkformed by a central void in an outer absorbent member which restrainsthe nits or the pocket or pouch containing the nits and which helpsmaintain the nits along the longitudinal axis of the article. Theabsorbent web below the nits also helps provide proper shaping and helpshold the nits against the body of the user, especially if the absorbentweb is a central rising member (hereafter described). Alternatively, anonabsorbent central rising member can be beneath the nits to help urgethem toward the body of the wearer.

With a central rising member below the nits or free-flowing particles.multiple discrete pockets can be helpful in reducing the tendency ofnits or free-flowing particles to shift to the sides when the centralportion of the pad is elevated by the action of the central risingmember. In one embodiment, the maximum transverse (lateral) width ofparticle-containing pockets is less than about 3 cm and specificallyless than about 2 cm. Discrete pockets of nits can be formed byadhesively laminated two fibrous webs together with regions of adhesivematerial joining the webs, according to principles known for formationof pockets of superabsorbent material in U.S. Pat. No. 5,030,314,“Apparatus for Forming Discrete Particulate Areas in a CompositeArticle,” issued to T. B. Lang, Jul. 9, 1991, herein incorporated byreference, or according to other methods known in the art.

In another embodiment, the absorbent core comprises a molded,three-dimensional high bulk wet laid cellulosic web, such as an uncrepedthrough-air dried web as taught by F. -J. Chen et al. in commonly ownedU.S. patent application, Ser. No. 08/912,906, “Wet Resilient Webs andDisposable Articles Made Therewith,” filed Aug. 15, 1997; U.S. Pat. No.5,429,686, issued to Chiu et al. on Jul. 4, 1995; U.S. Pat. No.5,399,412, issued to S. J. Sudall and S. A. Engel on Mar. 21, 1995; U.S.Pat. No. 5,672.248, issued to Wendt et al. on Sep. 30, 1997; and U.S.Pat. No. 5,607,551, issued to Farrington et al. on Mar. 4, 1997, all ofwhich are herein incorporated in their entirety by reference. Suchuncreped structures can offer a plurality of flow channels along thesurface of the web. When stacked or layered with other planar materialssuch as a polymer film, void space can still exist adjacent the surfaceof the tissue web to permit rapid flow of fluid parallel to the plane ofthe tissue web. Further, the uncreped tissues show excellent wetresiliency and high bulk under load when wet. Without wishing to belimited by theory, it is believed that the three-dimensional surfacestructures of such textured webs can maintain their shape and bulk whenwet because the hydrogen bonds defining the arrangement of the fibersare formed in the molded, three-dimensional state, so the structure doesnot relax to a flat state when wetted.

Absorbent Components of the Core

The absorbent article generally comprises an outer absorbent member orouter shaping member and further comprises a central absorbent memberlocated on, within, or beneath the outer absorbent member or outershaping member, wherein the central absorbent member comprises a pouchof free-flowing particles. In embodiments where the pouch offree-flowing particles is intended to serve a major absorbent component(e.g., absorbent capacity of about 10 g or greater) as opposed to anintake strip, the outer absorbent member or outer shaping member canhave a central void or depression for receiving the central absorbentmember comprising a pouch of free-flowing particles, wherein the wallsof the central void or depression provide lateral restraint to the pouchto prevent undesired deformation toward the longitudinal sides of thearticle. The pouch can be disposed on the body-side surface of the outerabsorbent member or outer shaping member or facing the body-side butdisposed within a central void in the outer absorbent member or outershaping member.

The outer shaping member is not necessarily absorbent but providesshaping to the article, and can be a closed cell foam, or any absorbentmaterial as well. If the central absorbent member has suitable capacityand especially if a wicking barrier is in place to prevent leakage tothe outer shaping member, the outer shaping member need not absorb fluidto serve a useful function in an article capable of good performance.However, the outer member can be absorbent while also providing shapingfunctionality. If the central absorbent member has adequate absorbentcapacity and especially if a wicking barrier is in place, it is unlikelythat the outer absorbent member will become significantly moistened inuse, in which case a low-cost material with poor wet resiliency can beused, such as ordinary fluff pulp or airfelt, without loss ofperformance.

In general, the absorbent core may be manufactured from a wide varietyof liquid absorbent materials commonly used in disposable sanitarynapkins, diapers, and other absorbent articles. Examples of suitableabsorbent materials include comminuted wood pulp which is generallyreferred to as airfelt or fluff pulp, creped cellulose wadding,absorbent foams, absorbent sponges, synthetic staple fibers, polymericfibers, hydrogel-forming polymer gelling agents, or any equivalentmaterials or combinations of materials.

The absorbent materials of the absorbent core, including the outerabsorbent member or other members, can comprise one or more plies ofwetlaid or airlaid tissue; cellulosic airlaid webs of comminuted fibers(commonly termed “airfelt”); other dry laid webs; creped cellulosewadding, absorbent foams; absorbent sponges; synthetic staple fibers;polymeric fibers; hydrogel-forming polymer gelling agents, or anyequivalent materials or combinations of materials. Other usefulmaterials include cellulose-superabsorbent mixtures or composites;hydroentangled webs comprising cellulosic fibers; composites ofsynthetic fibers and papermaking fibers; rayon; lyocell or othersolvent-spun hydrophilic fibers, such as those disclosed in U.S. Pat.No. 5,725,821, issued Mar. 10, 1998 to Gannon et al., hereinincorporated by reference; cellulosic foams including regeneratedcellulose foams; hydrophilic, flexible foams; fiber-foam composites;absorbent nonwoven webs; cotton; wool; keratin fibers; peat moss andother absorbent vegetable matter; the foam-structured fibrous absorbentmaterials of F. -J. Chen et al. disclosed in the commonly owned,copending U.S. patent application “Fibrous Absorbent Material andMethods of Making the Same,” Ser. No. 09/083,873, filed May 22, 1998,herein incorporated by reference; or absorbent foams produced from highinternal phase emulsions (HIPE) or other means, such as the foamsdisclosed in U.S. Pat. No. 5,692,939, issued Dec. 2, 1997 to DesMarais,U.S. Pat. No. 5,851,648, issued to K. J. Stone et al., Dec. 22, 1998, orin U.S. Pat. No. 5,795,921, issued Aug. 18, 1998 to Dyer et al., all ofwhich are herein incorporated by reference. The absorbent materials ofthe absorbent core can also comprise corrugated absorbent materials forenhanced longitudinal transport of fluid, such as the materialsdisclosed in U.S. Pat. No. 4,578,070, issued Mar. 25, 1986 to Holtman,herein incorporated by reference in its entirety. In one embodiment, atleast one layer of the absorbent core comprises cellulosic fibers andPET (polyethylene terephthalate) staple fibers, such as from about 5% toabout 20% staple fibers by weight, to provide increased wet resiliencyand integrity of the absorbent core.

A commercially available air-laid web is AIRTEX™ 395 air-laid web soldby James River Corporation located in Green Bay, Wis. AIRTEX 395air-laid web is 100% virgin softwood held together by an acrylic binder.Concert Fabrication Ltee, of Ontario. Canada, also produces a variety ofdensified airlaid webs held together with thermoplastic binder material.Other useful densified airlaid webs include the layered materialscomprising superabsorbent particles and cellulosic fibers disclosed inU.S. Pat. No. 5,866,242, issued Feb. 2, 1999 to Tan et al., hereinincorporated by reference.

A particularly useful cellulose-polymer composite material is coform, ahydraulically entangled mixture of pulp fibers and polymer, such as thematerials disclosed in U.S. Pat. No. 4,879,170, issued Nov. 7, 1989 toRadwanski et al.; U.S. Pat. No. 4,100,324 to Anderson et al. issued Jul.11, 1978, and U.S. Pat. No. 5,350,624 to Georger et al. issued Sep. 27,1994, or the materials made by the methods of Lau et al. in U.S. Pat.No. 5,711,970 issued Jan. 27, 1998, all of which are incorporated hereinby reference in their entireties.

Any suitable form of cellulosic material can be incorporated in theabsorbent materials of the absorbent core, including wood fibers, suchas bleached kraft softwood or hardwood, high yield wood fibers, andchemithermomechanical pulp fibers; bagasse; milkweed; wheat straw;kenaf; hemp; or peat moss. High yield fibers can be used to makeabsorbent members, exemplified by the high-yield airfelt disclosed inU.S. Pat. No. 4,247,362, issued to J. C. Williams, Jan. 27, 1981, hereinincorporated by reference. The fibers can also be crosslinked,suffonated, mercerized, heat treated, mixed with thermoplasticstabilizer fibers, or treated with wet strength agents. Caustic-treatedfibers, such as those made according to U.S. Pat. No. 5,858,021,“Treatment Process for Cellulosic Fibers,” issued to Tong Sun and ShengHu, Jan. 12, 1999, herein incorporated by reference, can be especiallybeneficial in providing good absorbency and bulk properties. Mixtures ofvarious fibers can be used, including coform, which comprisesthermoplastic fibers and wood fibers deposited together in an airlayingprocess.

The absorbent materials of the absorbent core can comprise chemicallymodified cellulose, including any known cellulose derivatives, such as2,3-dialdehyde cellulose or other cellulosic polymers derived therefrom,including those of K. Rahn and T. Heinze in “New Cellulosic Polymers bySubsequent Modification of 2,3-Dialdehyde Cellulose,” CelluloseChemistry and Technology, 32: 173-183 (1998), including sodium bisulfiteadducts of 2,3-dialdehyde cellulose or various carboxy cellulosecompounds. The modified cellulose compounds may be in powder, fiber, orfilm form. Likewise, acetylated cellulose may be used, as well ascellulosic fibers or films prepared from solutions of polysaccharides,particularly cellulose, in an aqueous tertiary amine N-oxide solvent,especially N-methylmorpholine N-oxide (NMMO); lyocell fibers inparticular may be used, including those of U.S. Pat. No. 5,837,184,“Process for the Production of Cellulose Fibres Having a ReducedTendency to Fibrillation,” issued to H. Firgo, Nov. 17, 1998, hereinincorporated by reference.

The absorbent core can also comprise the crinkled, quilted, absorbentpad disclosed in U.S. Pat. No. 4,650,481, issued Mar. 17, 1987 toO'Connor et al., herein incorporated by reference. The quilted form canbe obtained in the pouch filled with particles by stitching or bondingcertain portions of the encasement together.

Absorbent materials with high wicking fluxes can also be used in thepresent invention, including the materials of U.S. Pat. No. 5 843,852,“Absorbent Structure for Liquid Distribution,” issued to J. Dutkiewiczet al., Dec. 1, 1998, herein incorporated by reference. Multilobalfibers or fibers with complex extruded cross-sections for high wickingflux can also be incorporated in the present invention.

The article may also comprise hydrophobic material around the sides ofthe absorbent core to further reduce edge leakage. For example,hydrophobic fibers may be placed in discrete areas, such as around theperiphery of the hydrophilic absorbent core, to provide barriers againstleakage, as exemplified in U.S. Pat. No. 5,817,079, “Selective Placementof Absorbent Product Materials in Sanitary Napkins and the Like,” issuedto R. Bergquist et al., Oct. 6, 1998, herein incorporated by reference.A related approach which can be applied to the present invention isgiven by Csillag in U.S. Pat. No. 4,015,604, issued Apr. 5, 1977. Anabsorbent product is disclosed with side leakage control meanscomprising a narrow longitudinally extending zone along each side edgeof the product but spaced away from each of the side edges. This zone isimpregnated with a liquid hydrophobic material from the garment facingsurface to the body facing surface of the product. The hydrophobicimpregnate is applied to a hydrophilic pad as the pad passes through themanufacturing equipment. Likewise, Canadian Patent No. 884,608 issued toLevesque, Nov. 2, 1971, relates to treating the edges of a sanitarynapkin product with hydrophobic material in order to prevent sideleakage. In accordance with Levesque, the absorbent layer in the zone ofthe edges of the absorbent material is rendered hydrophobic while beingmaintained in a gas and moisture vapor permeable condition. Thehydrophobic zone may be coated with a liquid repellent composition orchemically modified to render the fibers hydrophobic. In theseembodiments with added hydrophobic fibers or hydrophobic matter towardthe longitudinal sides of the absorbent core, a wicking barrier such asa polymeric film can pass over at least a portion of the surface of thehydrophobic areas in the crotch region of the absorbent core.

In many embodiments, a central pouch of nits is attached to anunderlying absorbent layer to form a central absorbent member, and thecentral absorbent member is placed on the surface of or within a centralvoid in an outer absorbent member. A wicking barrier can also be presentto separate at least a portion of the central absorbent member from theouter absorbent member such that fluid communication between the twomembers is reduced.

The Wicking Barrier

The wicking barrier comprises one or more segments of a barrier materialthat impedes wicking from a central absorbent member or from a pouch ofnits to laterally adjacent absorbent material or to absorbent materialbeneath the central absorbent member or from a pouch of nits. Thebarrier material can be a polymeric film or plastic film; a nonwovenweb; a layer of rubber, silicone, or other non-absorbent materials; or aless pervious paper sheet including, for example, glassine, wax paper,impregnated papers, paper-polymer composites, densified tissue, paper ortissue containing internal sizing to render it less hydrophilic, paperor tissue treated with hydrophobic matter such as wax, silicone,thermoplastic material, or polyolefins. Flexible hydrophobic foams mayalso be used, such as a closed-cell polyurethane foam or a siliconefoam. A hydrophobic web such as a bonded carded web of a polyolefin(such as materials commonly used for surge layers in diapers, butwithout surfactants or other hydrophilic treatments) can also be used,provided that a useful barrier function is achieved. Such materials caninclude the transfer delay barrier materials disclosed in the commonlyowned U.S. patent application Ser. No. 60/079,657, “An Absorbent Systemfor Personal Care Products Having Controlled Placement of Visco-ElasticFluids” by A. S. Burnes et al., previously incorporated by reference.

The barrier material can also comprise hydrophobic matter that is usedto impregnate a portion of the outer absorbent member or a portion ofthe central absorbent member to reduce lateral wicking. Such hydrophobicmatter can include adhesives and particularly hot melt adhesives addedto the absorbent article while molten; wax; pastes or emulsionscomprising waxes; silicone-based fluids, gels, pastes, or caulk;phenolic resins or other resins which are cured after impregnating thefibrous material of the central absorbent member or outer absorbentmember; polyolefins or other plastic or hydrophobic material added aspowder, particularly sintered powder, or held in place by adhesives, orby thermal bonding. In addition to the impregnating material, whichhelps prevent lateral fluid flow in the article, there can be a distinctbreak, gap, or slit between the central absorbent member and the outerabsorbent member in the crotch region to further impede fluidcommunication, especially by removing or severing fibrous pathwaysbetween the central absorbent member and the outer absorbent member.

The barrier material can be placed along a portion of the perimeter of acentral absorbent member to reduce or prevent wicking to the surroundingouter absorbent member. In such an embodiment, the wicking barrier cancomprise a thin layer of a hydrophobic material such as a polymericfilm, a nonwoven web, a thermoplastic material, a layer of hot meltadhesive, or a flexible material such as a wax impregnated in the fibersadjacent the perimeter of the central absorbent member. When the wickingbarrier is a polymeric film or nonwoven web, it can have radialdimensions when set in place slightly greater than the radial dimensionsof the central absorbent member such that a strip of the material restson the surface of the absorbent core to define a visible barrier alongat least a portion of the perimeter of the central absorbent member.

Examples of absorbent core construction incorporating wicking barriersand related structures are disclosed in commonly owned copendingapplications Ser. No. 09/165,875, “Absorbent Article with Center FillPerformance,” filed Oct. 2, 1998, Ser. No. 09/165,871, “AbsorbentArticle Having Good Body Fit Under Dynamic Conditions,” also filed Oct.2, 1998; and Ser. No. Unknown, “Center-Fill Absorbent Article with aWicking Barrier and Central Rising Member,” filed Oct. 1, 1999 by Chenet al.; all of which are herein incorporated by reference.

Central Rising Member

The central rising member is a structure generally beneath the centralabsorbent member, or beneath the pouch filled with free-flowingparticles in particular, and above the backsheet which causes thecentral absorbent member (or at least a portion thereof) in the crotchregion of an absorbent article to deflect upward when the absorbentarticle is laterally compressed in the crotch region from thelongitudinal sides of the article. The central rising member can be aflexible absorbent material such as densified airlaid pulp fibers,coform, or one or more layers of creped or uncreped tissue, adapted withbending lines, scoremarks, flexure points, and/or folded sections suchas an “e”-folded web such that lateral compression from the longitudinalsides of the central rising member causes at least a portion of thecentral rising member to deflect upwards with sufficient force orresiliency that the overlying central absorbent member can be deflectedor urged toward the body. An absorbent central rising member can also beconfigured as a flattened tube.

The central rising member can comprise a at least one ply of a resilientmaterial having a wall thickness, an internal void within the resilientmaterial, present due to folding or layering of the material, whereinthe z-direction thickness of the internal void increases in size duringlateral compression as the upper surface of the central rising member isdisplaced upward. Alternatively, the central rising member can lack aninternal void, being a single layer of material that is folded orcreased to form an inverted V-shape or U-shape when the longitudinalsides thereof are moved inward toward the initial longitudinalcenterline of the central rising member.

The central rising member can comprise a thermoplastic deformationelement as disclosed by K. B. Buell in U.S. Pat. No. 5,300,055, issuedApr. 5, 1994, herein incorporated by reference, but the central risingmember can also be non-thermoplastic such as a densified cellulosic web.Thus, the central rising member can have a flexure means, andparticularly a longitudinally extending flexure hinge, for inducing thebody facing surface of the central rising member to have a convex upwardconfiguration when the sanitary napkin is worn. In an alternativeembodiment, the deformation element has a central region having a “W”shaped cross-section wherein the body facing surface of the centralrising member having the convex upward configuration is located in thecentral region, generally symmetrically between the longitudinal sideedges of the napkin. In another embodiment, the central rising memberhas a cup-shaped front region and a back region having a convex upwardconfigured body-facing surface.

In one embodiment, the central rising member can be a flattened, rolledtissue or paper structure including “e”-folded materials, with acenterline aligned with the longitudinal axis of the article (the flatcross-bar of the “e”-shape lying in the transverse direction, normal tothe longitudinal axis of the article). Upon lateral compression from thelongitudinal sides of the article, the flattened “e”-shape deflectsupwardly, the upper loop of the “e”-shape springing back into theapproximate shape of a semicircle to urge the upper surface of thecentral absorbent member toward the body of the wearer.

The central rising member can also comprise the liquid pervious spacingstructure for moving the topsheet away from the core, as disclosed by R.B. Visscher et al. in U.S. Pat. No. 5,324,278, issued Jun. 28, 1994,herein incorporated by reference.

Detailed examples of central rising members and their construction aredisclosed in the commonly owned copending application, Ser. No. Unknown,“Center-Fill Absorbent Article with a Wicking Barrier and Central RisingMember,” filed Oct. 1, 1999 by Chen et al.; herein incorporated byreference in its entirety, which also provides further details onoptions for topsheets, backsheets, and other members of the absorbentcore.

EXAMPLES Example 1 Nit Preparation with a BIVIS Disperger

Bahia Sul eucalyptus pulp sheets were disintegrated using a GrubbensPulper (Medium Consistency Pulper Model 01R, Cellwood Grubbens AB,Sweden) at approximately six percent consistency. Pulp was disintegratedabout 30 minutes. Runs were performed with and without debonder. Forruns with debonder addition, the debonder was added after five minutesof disintegration.

At the end of pulping, the pulp was diluted to about 4.5% consistencyand pumped over to the dump chest of a Bivis device while the agitatorwas running. The Bivis disperger (commonly termed an extruder by themanufacturer) was Model BC-45, manufactured by Clextral Inc., Firminy,France. Pumping was achieved using a pulper dump pump. The Bivis dumptank transfer pump was set to be in the recirculating mode. An Andritzbelt press (Continuous Belt Press, Model CPF 0.5 meter, P3,Andritz-Ruthner, Inc., Arlington, Tex.) was used to dewater the pulp anddischarge it into a screw conveyor system. Once activated, the feedvalve off the Bivis Dump Tank Transfer Pump was opened and therecirculation valve was closed. The belt press was configured to give adischarge mat 2.5 cm thick. Discharge consistency was approximately 32percent. This mat was broken up by the break-up screw at the end of thebelt press and then was transferred by the screw conveying system to thefeed hopper of the Bivis extruder.

Pulp was further disintegrated by the double feed screw system in thebottom of the feed hopper. The disintegrated pulp was fed to the Bivisfeed screw and directly into the Bivis extruder. The Bivis extruder is adouble screw, co-rotating extruder with the internal screw profile givenin Table 1. All screw elements were single flight.

TABLE 1 Zones in the Bivis Extruder. Element Screw Length Pitch Slotwidth Bivis Zone No. Type (mm) (mm) (mm) Feed 1 T1F 100 50 none Feed 2T1F 100 50 none 1 3 T1F 100 33 none 1 4 T1F 50 25 none 1 5 RH6 50 −15 62 6 T1F 100 33 none 2 7 T1F 50 25 none 2 8 RH6 50 −15 6 3 9 T1F 100 33none 3 10 T1F 50 25 none 3 11 RH6 50 −15 6 Discharge 12 T1F 100 33 noneDischarge 13 T1F 100 33 none

Two extraction zones were used for all runs. Extraction plates wereinstalled in Zones 1 and 2. Water and pulp fines were extracted fromthese zones.

For all samples, an attempt was made to control specific energy to alow-to-intermediate level in one set of runs and to high specific energyfor another set of runs. Temperature was recorded. Maximum temperaturegenerally correlates directly to specific energy, but maximumtemperature tended to migrate toward Zone 1 as time progressed.

Ranges of the above parameters are given in Table 2 below:

TABLE 2 High and Low Process Values for the BIVIS-produced Nits. LowHigh Specific Energy (kW-h/T) 90.4 218.3 Outlet Consistency (%) 46.855.1 Max Temperature (° C.) 99 116

The debonder was a quanternary ammonium compound, MacKernium™ 516Q-60(McIntyre Group, Ltd., Chicago, Ill.) added at a dose of 2.78 kg (6.15pounds) per metric ton.

Nits prepared were then oven dried overnight at 43° C.

Example 2 Nit Preparation using a Maule Disperger

About 800 kg of Bahia Sul bleached eucalyptus kraft pulp weredisintegrated using a Sulzer Escher-Wyss High Consistency Pulper (ModelST-C-W, Voith-Sulzer PaperTech, formerly Sulzer Escher-Wyss Gmbh,Ravensburg, West Germany). Pulp was disintegrated for 30 minutes at 12%to 15% consistency. At the end of 30 minutes, pulp was diluted toapproximately 4% consistency and pumped to a first chest. Slurry wasthen pumped at approximately 4% consistency from the first chest to aBlack-Clawson Double Nip Thickener® (Model 200, Black Clawson,Middletown, Ohio) where it was dewatered to approximately 12%consistency and fed via screw conveyor to the headbox of the AndritzBelt Press (Andritz-Ruthner, Inc., Arlington, Tex.).

Pulp was discharged from the Belt Press at approximately 35% consistencyto a break-up screw and thence to the Maule kneader/disperger by aheating screw, to raise the kneader inlet temperature to 80° C. Kneaderoutlet temperature was approximately 100° C. Target specific energy forthe kneader was 98 kW-hr/ton (5.5 horsepower-days per ton).

One run was performed using the preceding procedure with the followingexception: The outlet door to the kneader was closed and the kneader wasoperated with a rotor speed of 48 rpm for 10 minutes. This resulted in ahigher energy input to pulp, causing the nits to be smaller with fewerfibers projecting from the surface of the nits, resulting in animprovement in the flowability of the nits.

Example 3

Bleached kraft eucalyptus pulp from Cenibra, Inc. was disperged in aMaule disperger at an entry temperature of about 25° C. (roomtemperature) and an inlet consistency of 20% to form nits. Berocell 584debonder was added a level of 3 kg/ton prior to disperging. Nits werespread onto flat surfaces to a depth of about 2 cm and air driedovernight. The nits proved to be free flowing and were substantiallyfree of free fibers rising from the surfaces of the nits that couldcause entanglement between nits. The nits were screened to a size rangebetween about 300 and 850 microns and then encased in spunbond nonwovenwebs and sealed with heat sealing to produce particulate pouchessuitable for incorporation into absorbent articles.

Example 4

Bleached kraft eucalyptus pulp from Aracruz, Inc. (Brazil) was dispergedin a Maule disperger (Maule Type GR 11 manufactured by Ing. S. Maule &C. S.p.A., Torino, Italy) at an entry temperature of about 25° C. (roomtemperature) and an inlet consistency of 20% to form nits. Nits wereprepared with and without MacKernium 516Q-60 debonder. When added, thedebonder was present at a dose of 2.78 kg (6.15 pounds) MacKernium516Q-60 debonder per metric ton of pulp. The nits were made on the Maulemachine and oven dried over night at 43° C. The nits were sieved todifferent size particles as listed below in Table 3. Nits in the sizerange from 300 to 600 micrometers were used in subsequent production ofabsorbent articles for other Examples. The percentage of yield at thedifferent particle sizes show a significant difference between debondedversus non-debonded eucalyptus nits. Although a one useful particle sizedistribution range is from 300 to 850 microns, for some embodiments auseful range can be from 300 microns to 600 microns for good containmentof the nits and product comfort. Larger nits, in some cases, can morelikely be perceived as grainy or uncomfortable.

Surprisingly, the percent yield for the particle size range 300 micronsto 600 microns was much higher when debonder had been added to the pulpthan without debonder.

TABLE 3 Particle Size Distribution and Percentage of Yield forEucalyptus Nits Debonder Added No Debonder Screen Particle Size, % perScreen % per Screen Number microns (n = 4) (n = 4) 20 >850 41.35 62.5 30600-850 24.71 19.5 50 300-600 34.52 12.2 Pan <300 3.39 0.82

Table 4 shows the difference between debonded versus non-debondedeucalyptus nits in terms of Centrifuge Retention Capacity values (n=2),as measured according to the Method for Determining Centrifuge RetentionCapacity given above. The addition of debonder improves the CentrifugeRetention Capacity value—a surprising result given that the debonder hasa hydrophobic nature. The debonder was MacKernium 516Q-60 at 2.78 kg(6.15 pounds) per metric ton of pulp. The eucalyptus nits were made onthe Maule machine and oven dried over night at 43° C. The control codeswere non-debonded Weyerhauser NB416 pulp and debonded Weyerhaeuser NF405pulp. Pulp-based materials with debonder normally reduce the centrifugeretention capacity value as shown.

TABLE 4 Centrifuge Retention Capacity Values for Maule-producedEucalyptus Nits Debonded Non-Debonded Screen Number Particle Size CRC(g/g) CRC (g/g) As ls 300-850 2.3 1.4 20 850 2.6 1.6 30 600 2.0 1.6 50300 2.3 1.5 NB416 NA — 5.7 NF405 NA 3.9 —

The fluid intake and flow back values of eucalyptus nits is anotherproperty which can be considered. A fast intake and low flow back valuecan be useful in some embodiments. Table 5 shows the fluid intake andflow-back on the raw material (the Maule-produced eucalyptus nits),performed according to the Raw Material Absorbency Rate and Rewet TestMethod given above. In this test, the third insult is 1 ml, while thefirst two use 2 ml of fluid. Surprisingly, the time required for takingin the second insult is generally roughly the same as the time requiredfor the first insult, and the time required for the third insult whendoubled to normalize it to 2 ml is still only slightly greater thanrequired for the first or second insults. In other words, in the RawMaterial Absorbency Rate and Rewet Test, the nits of the present exampleshow an ability to take fluid in at a high rate even after multipleinsults.

In Table 5, on average, the non-debonded nits had higher flow-backvalues than those with the MacKernium 516Q-60 debonder.

Table 6 shows the fluid intake and flow-back for eucalyptus nitsenclosed in a pouch or “pillow case,” prepared and measured according tothe Intake and Rewet Test given above. The non-debonded nits also hadhigher flow-back values than those with the MacKernium 516Q-60 debonder.Fluff based products normally have fast intake and high flow backvalues. The intake times for the three insults when tested with theencased material showed increasing times required for multiple insults.

TABLE 5 Maule-produced Nits Intake Times and Flow Back Values for theRaw Material Screen Insult 3 Flow Number Insult 1 (sec) Insult 2 (sec)(sec) Back 3 (g) Debonded As Is 29.6 29.6 17.3 0.57 Non- As Is 26.5 29.315.1 0.67 Debonded Debonded 20 28.0 28.6 14.9 0.67 Non- 20 30.3 30.718.8 0.77 Debonded Debonded 30 28.1 30.5 17.7 0.85 Non- 30 28.0 29.415.9 0.59 Debonded Debonded 50 28.8 30.1 16.9 0.55 Non- 50 28.5 31.418.1 0.77 Debonded Debonded 30-50 29.0 33.2 19.6 0.92 Non- 30-50 29.230.6 16.5 0.62 Debonded

TABLE 6 Maule-produced Nits Intake Times and Flow Back for EncasedMaterial Flow Flow Flow Screen Insult 1 Back 1 Insult 2 Back Insult BackNumber (sec) (g) (sec) 2 (g) 3 (sec) 3 (g) Debonded As Is 10.8 0.15 23.50.24 53.6 0.42 Non- As Is 10.7 0.40 12.9 0.50 21.2 0.58 DebondedDebonded 20 10.7 0.05 22.5 0.13 40.0 0.33 Non- 20 8.7 0.26 11.4 0.3816.1 0.52 Debonded Debonded 30 13.0 0.15 31.6 0.24 60.7 0.28 Non- 30 9.30.49 13.7 0.53 21.0 0.50 Debonded Debonded 50 10.0 0.13 33.7 0.17 57.00.27 Non- 50 11.4 0.54 21.3 0.67 35.6 0.63 Debonded Debonded 30-50 10.40.14 25.3 0.12 46.8 0.20 Non- 30-50 9.9 0.45 14.0 0.55 20.7 0.54Debonded NB416 — 18.1 0.18 97.9 0.11 230.5 1.3 CF405 — 32.0 0.43 189.60.36 >300 NA

Permeability testing was performed to determine the acceptable range ofpermeability for debonded Eucalyptus nits compared to three controlmaterials. The control materials were non-debonded eucalyptus nits,CF-405 pulp from Weyerhaeuser Corporation (a debonded pulp), and NB416pulp from Weyerhaeuser Corporation. The test method used to determinepermeability was the Gel Bed Permeability test given above and the flowback test method was Intake and Rewet Test Method given above (for nitsencased in a pouch). The data are summarized in Table 7 below.

TABLE 7 Permeability Data for Eucalyptus Nits. Flow Back PermeabilityScreen size Values (g) (10⁻⁹ cm²) Debonded 30-50 0.14 528 EucalyptusNits Non-Debonded 30-50 0.45 1372 Eucalyptus Nits CF-405 400 gsm,densified 0.43 618 to .076 g/cc NB-416 400 gsm, densified 0.18 549 to.076 g/cc

A high permeability permits rapid fluid intake. A high permeabilityvalue for eucalyptus nits correlates to a high rewet value which createsa wet surface against the body. Lower permeability allows for fast fluidintake but less available void volume, which allows the fluid to beabsorbed and retained by the material. The lower the permeability value,the less viscoelastic fluids are able to pass directly through theabsorbent bed. In some embodiments, the viscoelastic fluids areselectively retained with the nits, yielding higher capacity and lowerrewet values. A used permeability range is believed to exist below about7×10⁻⁷ cm², such as a range between about 3×10⁻⁷ cm² and about 7⁻⁷×10,or, more specifically, between about 4.5×7.0⁻⁷ cm² and about 7⁻⁷×10.Permeability results showed that debonded eucalyptus nits were in thesame range for treated and non-treated fluff but were outside thenon-debonded eucalyptus nits permeability values.

The nits sieved within the size range of 300 micrometers to 600micrometers were then tested for cohesive strength, according to ASTMtest method D-6128. The Flowability Coefficient (FFC) was obtained,which is the ratio of consolidation pressure (σ₁) to cohesive strength(f_(c)) measured according to the Jenike shear flow test for particles,as specified in ASTM Test Method D6128-97, “Standard Shear TestingMethod for Bulk Solids Using the Jenike Shear Cell.” The testing wasperformed for Maule-produced nits both with and without debonder, withtesting performed by Jenike & Johanson, Inc. (Wesfford, Mass.). Resultsfor low, medium, and high consolidation are shown in Table 8. Theconsolidation pressure, σ₁, and the cohesive strength, “Str.”, are bothreported in both pounds per square foot (psf), as reported by thetesting firm, and in kPa. In addition to FFC (Flowability Coefficient),which is dimensionless, results are also shown for effective angle ofinternal friction (δ) and kinematic angle of internal friction (φ). TheFlowability Coefficient values greater than 2 and also greater than 3are indicative of a material with a degree of free flowing behavior.Nits with substantially higher flowability have been prepared, such asthose of Example 8 below, and are expected to have even higherFlowability Coefficients. For example, highly flowable particles for usein the present invention can also have a Flowability Coefficient of 3.5or greater or of about 4 or greater. The effective angle of internalfriction can also be related to flowability or tendency to bridge inhopper flow. The effective angle of internal friction can be from about40° to about 67°, or from about 40° to about 60°. The testing in thiscase did not show strong differences in the measured parameters for thenits with and without debonder.

TABLE 8 Jenike Shear Cell Data for Sieved Maule-produced Nits. Consoli-σ₁, σ₁, Str., Str., dation Sample psf kPa psf kPa FFC δ φ Low Debonder90 4.31 38 1.82 2.4 65° 57° Low No deb. 87 4.16 39 1.87 2.2 67° 60°Medium Debonder 362 17.32 116 5.55 3.1 62° 56° Medium No deb. 386 18.47135 6.46 2.9 62° 56° High Debonder 727 34.79 243 11.63 3 59° 52° High Nodeb. 720 34.46 199 9.52 3.6 60° 54°

Compressibility testing also performed by Jenike & Johanson yieldeddensity values of up to 232 kg/cubic meter (14.5 pounds per cubic foot)for both sets of nits tested, with a range of from 104 kg/cubic meter6.5 to 232 kg/cubic meter, with the variation due to possible voidsinside the bed of nits when the nits were poured into a contained.

Example 5

Eucalyptus nits were also produced on the BIVIS equipment describedabove. Table 9 lists the centrifuge retention capacity values foreucalyptus nits with MacKernium 516Q-60 debonder at three differentlevels. The eucalyptus nits were oven dried over night at 43° C. Anincrease in debonder did not appear to reduce the absorbent capacity ofthe nits.

The control codes were non-debonded Weyerhaeuser NB416 pulp and debondedWeyerhaeuser NF405 pulp. Pulp-based materials with debonder normallyreduce the centrifuge retention capacity value as shown.

TABLE 9 BIVIS-produced Centrifuge Retention Capacity Values DebonderLevel (kg/metric ton Sample Particle Size of pulp) CRC (g/g) Eucalyptusnits 300-850 0.68 1.6 Eucalyptus nits 300-850 2.78 1.2 Eucalyptus nits300-850 4.54 1.6 NB416 NA NA 5.7 NF405 NA NA 3.9

The fluid intake and flow back values were measured and are shown inTable 10, measured according to the Raw Material Absorbency Rate andRewet Test Method. These results show how the specific type of debonderdoes not inhibit fluid intake or increase the flow-back valuesindependent of the amount of debonder.

TABLE 10 BIVIS-produced Raw Material Intake Times and Flow Back ValuesDebonder Level Energy (lbs./metric Level Insult 1 Insult 2 Insult 3 FlowBack Sample ton of pulp) (Amp) (sec) (sec) (sec) 3 (g) As Is 1.5 58 28.130.0 20.9 0.90 As Is 1.5 94 27.6 31.7 21.4 0.93 As Is 6.17 67 28.8 29.615.9 0.81 As Is 6.17 102 28.2 30.9 17.0 0.84 As Is 10.0 62 28.1 31.618.9 0.94 As Is 10.0 100 30.6 33.4 19.6 0.96

Example 6

A small scale non-menstrual use test was run on the Maule producednon-debonded and debonded eucalyptus nits of Example 4. The nits weresieved to four different particle sizes. 3.0 grams of dry nits wereplaced in a nonwoven pouch and heat sealed on all edges. The pouch was95 mm long and 40 mm wide. The pouch was oval in shape and constructedof 40 gsm (1.2 osy) pink prism on the top and 20 gsm white SMS(spunbond-meltblown-spunbond laminate) on the bottom. On the bottom ofthe pouch, 0.5 grams of superabsorbent material was attached withadhesive. The oval pouch was placed on top of and in the center of apre-cut, pre-adhesive sprayed hour glass shaped 90-gsm coform layer. Thecoform layer was 210 mm long and 65 m wide and constructed of 60 percentpolypropylene and 40 percent pulp. The coform was adhesively attached toa 20-micron thick polyethylene web serving as a backsheet. A 20-gsmspunbond cover was placed on top of the pouch and coform layer. Thecover stock was attached to the coform and the backsheet with adhesive,and the article was die cut to the same width and length of the coformto form a sanitary napkin. A two millimeter edge seal was embossedwithin the coform and was two millimeters from the edge of the coform.Nine subjects wore each code for one hour dry and one hour wet with 5milliliters of Astroglide® injected into the middle of the pouch.Astroglide® was injected into the center of the pouch using a syringeand needle and uniformly distributed in the pouch. Astroglide® is apersonal lubricant manufactured by BioFilm, Inc.(Vista, Calif.). Thesubjects completed a questionnaire to rate the following attributes: padcomfort, pad softness, and bulkiness. It is a combination of theseattributes which determine if a product is acceptable to wear by thewoman. The scale is from 1 to 7 with 7 being the best rating forcomfort, softness and least bulkiness of the product. The averagesubject attribute results are summarized in Tables 11 and 12. One usefuleucalyptus nits particle size range is from 20 to 50 mesh and morespecifically greater than 30 mesh but less than 50 mesh.

TABLE 11 Average Subject Attribute Ratings for Debonded Nits 30-50Attribute 20 Screen 30 Screen Screen 50 Screen Pad Comfort 6.5 6.0 6.36.5 Pad Softness 6.5 6.7 6.6 6.6 Bulkiness 6.4 6.6 6.6 6.6

TABLE 12 Average Subject Attribute Ratings for Non-Debonded Nits 30-50Attribute 20 Screen 30 Screen Screen 50 Screen Pad Comfort 6.5 6.5 6.66.7 Pad Softness 6.7 6.7 6.9 6.7 Bulkiness 6.2 6.6 6.6 6.6

Example 7

A 175-gsm airlaid densified web with a density of about 0.1 g/cc was cutto a dumbbell shape with a length of about 21.5 cm and a width at thetransverse centerline of about 6 cm. A central region of the outerabsorbent member was removed by a die cutting operation to provide acentral void in the outer absorbent member 42.7 cm long and 3.7 cm wide.The dumbbell-shaped outer absorbent member was placed on a 20-gsmpolyethylene backsheet provided with contact adhesive. The backsheet wassubstantially larger than the dumbbell-shaped absorbent web. Arose-colored 20-gsm polyethylene film was die cut to be a roundedrectangle 20.3 cm long by 4.7 cm in width and was centrally placed overthe central void to serve as a wicking barrier. 3.3 grams of loose nitswere then placed directly in the void over the wicking barrier.

The nits were made of bleached kraft eucalyptus fibers which had beenmechanically curled and disperged to form small dense flocs about 1 mmin diameter. The nits were prepared by taking 20 grams of dry eucalyptuspulp that had been previously disperged in the moist state (about 30%consistency) in a Maule disperger, then further moistening the pulp to aconsistency of about 20% and beating the fibers in a 4.7-liter (5-quart)Hobart mixer for 1.5 hours to create dense nits. The moist nits werethen spread out on a surface and air dried. FIG. 15 is a micrograph froma scanning electron microscope (SEM) showing a characteristic nit fromthis batch. The nit is substantially ovoid in shape and is substantiallyfree of loose fibers projecting from the surface of the nit that couldentangle with other nits. In some degree of contrast, FIG. 16 shows aform of a nit having projecting fibers rising from the surface of thenit.

The dry, loose nits were placed over the wicking barrier film inside thevoid of the outer absorbent member and covered with the a 20-gsmspunbond polypropylene topsheet, which served to hold the nits in placeand function as the upper half of an encasement, while the wickingbarrier served as the lower half of the encasement. The topsheet wasprovided with contact adhesive on the side toward the absorbent core,permitting it to join to the horizontal component of the wicking barrierand form a seal to hold the nits in place. The topsheet had also beentreated with 0.3% by weight of a surfactant comprising 45 wt. %polyethoxiated hydrogenated ethoxylated castor oil and 55 wt. % sorbitanmonooleate, available from ICI Americas (Wilmington, Del.).

After the topsheet was attached, the entire article was die cut with adumbbell-shaped die having dimensions greater than the outer absorbentmember (24.4 cm long, 8 cm wide at the transverse centerline) to providea rim of backsheet material and cover material around the outerabsorbent member in an absorbent article having good integrity providedin part by the contact adhesive on the polymeric film.

A loop of the colored barrier material was visible through thetranslucent topsheet (the horizontal component of the pink wickingbarrier).

The central absorbent member comprising nits was conformable, flexible,and had a comfortable, soft feel.

Example 8

Sanitary napkins were assembled generally according to Example 7, exceptthat the nits were first encased in an encasement comprising a 20-gsmspunbond polypropylene web. Experimental use tests with menstruatingsubjects were conducted using nits that were treated with debonder aswell as nits not treated with debonder. Based on visual appearance andleakage of the used products, the absorbent articles comprising nitstreated with debonder provided better intake and fluid handlingperformance.

While not wishing to be bound by any particular theory, it is believedthat the improvement in absorption of menses is due to the addition ofdebonder to the eucalyptus nits process which creates a positivelycharged surface on the eucalyptus fibers. Red blood cells are negativelycharged, and the positively charged surface on the eucalyptus nits isbelieved to attract and retain the negatively charged components inblood. A typical cationic debonder would be a quaternary ammonium saltof a fatty acid. As is well known to those who process wood pulp fibers,an aqueous solution of a debonder will spontaneously cover a cellulosesurface. In the case of a cationic debonder, the cellulose surface willthen become positively charged and will more effectively adsorbnegatively charged red blood cells and blood proteins. The absorption ofproteins and cells is believed to reduce the viscosity andviscoelasticity of the remaining fluid, thus improving intake anddistribution of the fluid throughout the absorbent core by wickingforces.

In a layered or gradient product design, the positively chargedeucalyptus nits can be placed on top of a superabsorbent material thatis adhered to or held against the bottom of the absorbent structure.This layering provides an upper layer of hydrophilic, charged materialwhich increases the removal of red blood cells and other negativelycharged components of blood by the eucalyptus nits. The superabsorbenton the bottom is then more efficient at pulling in the residual waterdue to this filtering of the red blood cells by the eucalyptus nits.This reduction of hematocrit before the superabsorbent layer reduces gelblocking and increases the superabsorbent's swelling capability.

Example 9

Nits exposed to two distinct disperging operations were prepared bytaking two 100 g portions of the dry, debonder-free Maule-producedeucalyptus nits of Example 4, and remoistening each portion with tapwater to a consistency of 20%. One portion was then sprayed-duringstirring with 3 g of “5% Silicone Mold Release,” product 3045 of CrownIndustrial Products, Hebron, Ill. (a copyright date of 1969 appears onthe spray can), a product comprising chlorinated solvents with 5%silicone. The spray application gave an estimated silicone add-on of0.15%. The two portions of nits were then separately disperged for 1.5hours. The silicone-treated nits were disperged in a KitchenAid Classicmixer, model K45SS (St. Joseph, Mich.), at the lowest speed, “stir.” Themoistened nits without silicone were disperged in a 4.7-liter (5-quart)Hobart mixer, Model N-50 of Hobart Canada (North York, Ontario, Canada).Disperging in both cases was performed for 1.5 hours. (Both theKitchenAid and Hobart mixers appear to be essentially the same deviceswith similar rotating speeds and rotors.) The nits from both fractionswere then dried for about 2.5 hours at 105° C.

Following treatment, both fractions had improved flowability relative tothe nits of Example 4. The silicone treated nits, however, had severaldifferent properties. The particle size distribution was finer that thatof the fraction without silicone, which had formed a large number ofmultiparticle clumps. Sieving gave the results in Table 13. The presenceof silicone during the second disperging step appears to have promoted anew particle size distribution, with the silicone-treated fractionhaving about half the mass of large nits (particles over 850 microns)compared to the fraction without silicone.

TABLE 13 Sieve Analysis for Twice Disperged Nits Screen Number ParticleSize, microns With Silicone Without Silicone 20 >850 35.10 67.73 30600-850 33.70 18.39 50 300-600 30.91 13.55 Pan <300 0.29 0.33

In spite of the clumps and larger particles in the fraction withoutsilicone, it had better flowability (evidenced by simple handling andpouring of the material within a plastic bag) than the originalMaule-produced nits. But the silicone-treated fraction had very fewclumps and very little tendency to coalesce, but flowed readily, similarto sand when held in the hands. The angle of repose for the siliconetreated fraction was measured at 57°. The fraction without the siliconedisplayed a slightly lower angle of repose, 51°, but the nits bridgedthe funnel twice during measurement and required pushing to urge themout of the funnel. Given the low mass of the particles, these angles ofrepose below 60° are believed to be good evidence of flowability or of alack of strong cohesive forces between the particles. Withoutlimitation, it is believed that the second disperging step improvedflowability by adding more energy to the nits to create dense, compactedstructure, by providing new shear conditions that could bring loosefibers into back into contact with the nits, and by allowing hydrogenbonds to form between loose fibers and their parent nits. Further,without wishing to be bound by theory, it is believed that the additionof silicone helped prevent clumping and may have allowed for betterbreak-up of nits during disperging to yield smaller particle sizes,while also enhancing lubricity between dry nits. Other lubricants anddebonders are expected to have a similar effect in promoting goodparticle size distribution during disperging, whether in a first orsecond disperging step.

Examples 10-16

By way of illustration, a variety of feminine care products can beprepared from the nits produced in any of the above Examples. In Example10, a pre-cut oval pouch made from polyolefin spunbond webs can befilled with nits and optionally with odor-control compounds such aszeolites and sealed around the edges ultrasonically or thermally. Thepouch can be attached to an underlying absorbent layer such as coform,airlaid or a fluff batt. A spunbond cover is placed over the pouch andattached with adhesive to form a sanitary napkin.

In Example 11, a pre-cut oval pouch can be filled with a layer ofsuperabsorbent on the bottom, with adhesive on the lower inner surfaceof the pouch helping to hold the superabsorbent particles, with nits areplaced on top of the superabsorbent. The pouch is attached to anabsorbent layer such as coform, airlaid or a fluff batt. A spunbondcover is placed over the pouch and attached with adhesive. A section ofan activated carbon fabric may also be attached to the coform for odorcontrol.

In Example 12, a liquid-pervious pouch is filled with superabsorbent andnits which are mixed together and the pouch is sealed around all edges.The pouch is attached to an absorbent layer such as coform, airlaid or afluff batt. A spunbond cover is placed over the pouch and attached withadhesive.

In Example 13, a layer of nits is sandwiched between a layer of lowbasis weight coform or airlaid (less than 120 gsm) and a spunbond coverand is sealed with heat around the edges.

In Example 14, a pantiliner is formed from a layer of nits comprisingeucalyptus fibers that is sandwiched between a layer of low basis weightcoform or airlaid (less than 120 gsm) and a backsheet. A spunbond coveris placed over the absorbent and the pantiliner is sealed with heataround the edges.

In Example 15, a tampon is filled with nits with or withoutsuperabsorbent and a nonwoven cover stock is wrapped around the nits forcontainment.

In Example 16, a tampon is filled in the center with nits with orwithout superabsorbent and a layer of airlaid or fluff batt is wrappedaround the nits and a cover stock material is attached to the airlaid orfluff batt.

It will be appreciated that the foregoing examples, given for purposesof illustration, are not to be construed as limiting the scope of thisinvention. Although only a few exemplary embodiments of this inventionhave been described in detail above, those skilled in the art willreadily appreciate that many modifications are possible in the exemplaryembodiments without materially departing from the novel teachings andadvantages of this invention. Accordingly, all such modifications areintended to be included within the scope of this invention, which isdefined in the following claims and all equivalents thereto. Further, itis recognized that many embodiments may be conceived that do not achieveall of the advantages of some embodiments, particularly of the preferredembodiments, yet the absence of a particular advantage shall not beconstrued to necessarily mean that such an embodiment is outside thescope of the present invention.

1. An absorbent article for use on the body of a wearer, the absorbentarticle having a longitudinal axis, a transverse axis, two longitudinalsides, a target zone and a body side, the absorbent article comprising:a) a liquid impervious backsheet; b) a liquid pervious topsheet attachedto the backsheet; c) a conformable intake member comprising a pouchcontaining free-flowing particles; d) an outer shaping member laterallysurrounding the pouch; and e) a wicking barrier between at least aportion of the pouch and the outer shaping member, wherein thefree-flowing particles have a Centrifuge Retention Capacity of about 1.5g/g or greater.
 2. The absorbent article of claim 1, wherein the wickingbarrier is a polymeric film.
 3. The absorbent article of claim 1,wherein the free-flowing particles comprise hardwood nits.
 4. Theabsorbent article of claim 1, wherein the pouch has a width of less thanabout 5 cm and a length of about 10 cm or greater.
 5. The absorbentarticle of claim 1, wherein the free-flowing particles comprise one ofpolymeric beads, hollow spheres, and mineral particles.
 6. The absorbentarticle of claim 1, wherein the free-flowing particles comprise at leastabout 30% nits by weight and no more than about 30% mineral matter byweight.
 7. The absorbent article of claim 1, wherein the free-flowingparticles are substantially free of clay.
 8. The absorbent article ofclaim 1, wherein at least 25% by mass of the free-flowing particles havea particle size above 300 microns.
 9. The absorbent article of claim 1,wherein the free-flowing particles have a mean particle size betweenabout 300 microns and about 600 microns.
 10. The absorbent article ofclaim 1, wherein the pouch further comprises an odor control agent. 11.The absorbent article of claim 1, wherein the free-flowing particlesfurther comprise one of an odor-control agent, an anti-microbial agent,and a surfactant.
 12. The absorbent article of claim 1, wherein thefree-flowing particles further comprise an enzyme.
 13. The absorbentarticle of claim 1, further comprising superabsorbent particles withinthe pouch.
 14. The absorbent article of claim 1, wherein thefree-flowing particles comprise cellulosic fibers and one of a debonder,a lubricant, a silicone compound, and a surfactant.
 15. The absorbentarticle of claim 1, wherein the free-flowing particles comprisecellulosic fibers treated with a quatemary amine debonder agent.
 16. Theabsorbent article of claim 1, wherein the free-flowing particlescomprise cellulosic nits with added hydrophobic matter on at least aportion of the surface of the nits.
 17. The absorbent article of claim1, wherein the free-flowing particles comprise cellulosic nits treatedwith 0.02% to 4% by weight of added hydrophobic matter, based on thetotal weight of the free-flowing particles and added hydrophobic matter.18. An absorbent article for use on the body of a wearer, the absorbentarticle having a longitudinal axis, a transverse axis, two longitudinalsides, a target zone and a body side, the absorbent article comprising:a) a liquid impervious backsheet; b) a liquid pervious topsheet attachedto the backsheet; c) a conformable intake member comprising a pouchcontaining free-flowing particles; and d) an outer shaping memberlaterally surrounding the pouch, wherein the free-flowing particles havea Flowability Coefficient of about 2 or greater.
 19. The absorbentarticle of claim 18, wherein the free-flowing particles also have aCentrifi.ige Retention Capacity of about 1.5 g/g or greater.
 20. Theabsorbent article of claim 18, wherein the pouch has a width of lessthan about 5 cm and a length of about 10 cm or greater.
 21. Theabsorbent article of claim 18, wherein the free-flowing particlescomprise hardwood nits.
 22. The absorbent article of claim 18, whereinthe free-flowing particles comprise one of polymeric beads, hollowspheres, and mineral particles.
 23. The absorbent article of claim 18,wherein the free-flowing particles comprise at least about 30% nits byweight and no more than about 30% mineral matter by weight.
 24. Theabsorbent article of claim 18, wherein the free-flowing particles aresubstantially free of clay.
 25. The absorbent article of claim 18,wherein at least 25% by mass of the free-flowing particles have aparticle size above 300 microns.
 26. The absorbent article of claim 18,wherein the free-flowing particles have a mean particle size betweenabout 300 microns and about 600 microns.
 27. The absorbent article ofclaim 18, wherein the pouch further comprises an odor control agent. 28.The absorbent article of claim 18, wherein the free-flowing particlesfurther comprise one of an odor-control agent, an anti-microbial agent,and a surfactant.
 29. The absorbent article of claim 18, wherein thefree-flowing particles further comprise an enzyme.
 30. The absorbentarticle of claim 18, further comprising superabsorbent particles withinthe pouch.
 31. The absorbent article of claim 18, wherein thefree-flowing particles comprise cellulosic fibers and one of a debonder,a lubricant, a silicone compound, and a surfactant.
 32. The absorbentarticle of claim 18, wherein the free-flowing particles comprisecellulosic fibers treated with a quatemary amine debonder agent.
 33. Theabsorbent article of claim 18, wherein the free-flowing particlescomprise cellulosic nits with added hydrophobic matter on at least aportion of the surface of the nits.
 34. The absorbent article of claim18, wherein the free-flowing particles comprise cellulosic flits treatedwith 0.02% to 4% by weight of added hydrophobic matter, based on thetotal weight of the free-flowing particles and added hydrophobic matter.